Revert back to UIKit for the presentation of the timeline media preview. (#3719)

* Revert back to UIKit for the presentation of the timeline media preview.

* Fix a presentation issue where the media is clipped until the animation finishes.

* Workaround for the preview controller replacing the info button when swiping.

* Use a self-sizing detent on the media info sheet.

ElementX.xcodeproj/project.pbxproj

@@ -273,6 +273,7 @@
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 		366D5BFE52CB79E804C7D095 /* CallScreenViewModelTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = CAD9547E47C58930E2CE8306 /* CallScreenViewModelTests.swift */; };
+		3684AD01C5FCB7616B28F629 /* TimelineMediaPreviewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5CDE60FEE95039CCCEEEE3B0 /* TimelineMediaPreviewController.swift */; };
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@@ -493,6 +494,7 @@
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 		62C5876C4254C58C2086F0DE /* HomeScreenContent.swift in Sources */ = {isa = PBXBuildFile; fileRef = A3B4B58B79A6FA250B24A1EC /* HomeScreenContent.swift */; };
 		63780F9DA06573E38A471ECA /* GenericCallLinkWidgetDriver.swift in Sources */ = {isa = PBXBuildFile; fileRef = 28C202C1C7E330F124981A31 /* GenericCallLinkWidgetDriver.swift */; };
+		6386EA3C898AD1A4BC1DC8A5 /* TimelineMediaPreviewModifier.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9FD40B92FCF20165658296AD /* TimelineMediaPreviewModifier.swift */; };
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 		63E46D18B91D08E15FC04125 /* ExpiringTaskRunner.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7B25F959A434BB9923A3223F /* ExpiringTaskRunner.swift */; };
 		642DF13C49ED4121C148230E /* TestablePreview.swift in Sources */ = {isa = PBXBuildFile; fileRef = B1E227F34BE43B08E098796E /* TestablePreview.swift */; };
@@ -770,7 +772,6 @@
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 		97BAEDD9054FB5F233EE928B /* EncryptionResetScreenModels.swift in Sources */ = {isa = PBXBuildFile; fileRef = 306AB507E1027D6C5C147EB6 /* EncryptionResetScreenModels.swift */; };
 		981853650217B6C8ECDD998C /* NavigationRootCoordinatorTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F875D71347DC81EAE7687446 /* NavigationRootCoordinatorTests.swift */; };
-		9826A4DBBEFA7041A9E0EFAD /* TimelineMediaPreviewScreen.swift in Sources */ = {isa = PBXBuildFile; fileRef = AA57E8563C346B13DDE4A6F4 /* TimelineMediaPreviewScreen.swift */; };
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 		9847B056C1A216C314D21E68 /* AuthenticationService.swift in Sources */ = {isa = PBXBuildFile; fileRef = F3A1AB5A84D843B6AC8D5F1E /* AuthenticationService.swift */; };
 		988BA75A182738150894A23F /* UserIndicator.swift in Sources */ = {isa = PBXBuildFile; fileRef = E8AE4B3273BA189FDCD4055C /* UserIndicator.swift */; };
@@ -952,7 +953,6 @@
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 		BEA646DF302711A753F0D420 /* MapTilerStyleBuilderProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 225EFCA26877E75CDFE7F48D /* MapTilerStyleBuilderProtocol.swift */; };
 		BEC6DFEA506085D3027E353C /* MediaEventsTimelineScreen.swift in Sources */ = {isa = PBXBuildFile; fileRef = 002399C6CB875C4EBB01CBC0 /* MediaEventsTimelineScreen.swift */; };
-		BFDDAF1A36FBC7CF63DCB7DD /* clear.png in Resources */ = {isa = PBXBuildFile; fileRef = 17F7A723A46DF5C95BE15EBF /* clear.png */; };
 		BFEB24336DFD5F196E6F3456 /* IntentionalMentions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0DF5CBAF69BDF5DF31C661E1 /* IntentionalMentions.swift */; };
 		C0090506A52A1991BAF4BA68 /* NotificationSettingsChatType.swift in Sources */ = {isa = PBXBuildFile; fileRef = 07579F9C29001E40715F3014 /* NotificationSettingsChatType.swift */; };
 		C022284E2774A5E1EF683B4D /* FileManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 04DF593C3F7AF4B2FBAEB05D /* FileManager.swift */; };
@@ -1254,7 +1254,6 @@
 		FDC67E8C0EDCB00ABC66C859 /* landscape_test_video.mov in Resources */ = {isa = PBXBuildFile; fileRef = 78BBDF7A05CF53B5CDC13682 /* landscape_test_video.mov */; };
 		FDD5B4B616D9FF4DE3E9A418 /* QRCodeScannerView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 92DB574F954CC2B40F7BE892 /* QRCodeScannerView.swift */; };
 		FDE47D4686BA0F86BB584633 /* Collections in Frameworks */ = {isa = PBXBuildFile; productRef = CAA3B9DF998B397C9EE64E8B /* Collections */; };
-		FE43747C116CA3D8D6B92F5F /* TimelineMediaPreviewCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = E3A62FBD3007312311C14DD8 /* TimelineMediaPreviewCoordinator.swift */; };
 		FE4593FC2A02AAF92E089565 /* ElementAnimations.swift in Sources */ = {isa = PBXBuildFile; fileRef = EF1593DD87F974F8509BB619 /* ElementAnimations.swift */; };
 		FEC03105D1BDE0F49BD7F243 /* PinnedEventsTimelineScreenModels.swift in Sources */ = {isa = PBXBuildFile; fileRef = 9B6572E6EF5D5F4B0C338A40 /* PinnedEventsTimelineScreenModels.swift */; };
 		FEFD5290B31FCBA6999912C8 /* RoomChangePermissionsScreenViewModelProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2721D7B051F0159AA919DA05 /* RoomChangePermissionsScreenViewModelProtocol.swift */; };
@@ -1450,7 +1449,6 @@
 		16D09C79746BDCD9173EB3A7 /* RoomDetailsEditScreenModels.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomDetailsEditScreenModels.swift; sourceTree = "<group>"; };
 		1715E3D7F53C0748AA50C91C /* PostHogAnalyticsClient.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PostHogAnalyticsClient.swift; sourceTree = "<group>"; };
 		17A8AA0DFA06012A9DAB951E /* TimelineProxyMock.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineProxyMock.swift; sourceTree = "<group>"; };
-		17F7A723A46DF5C95BE15EBF /* clear.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = clear.png; sourceTree = "<group>"; };
 		18486B87745B1811E7FBD3D2 /* AnalyticsPromptScreenModels.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AnalyticsPromptScreenModels.swift; sourceTree = "<group>"; };
 		184CF8C196BE143AE226628D /* DecorationTimelineItemProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DecorationTimelineItemProtocol.swift; sourceTree = "<group>"; };
 		18F2958E6D247AE2516BEEE8 /* ClientProxy.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ClientProxy.swift; sourceTree = "<group>"; };
@@ -1792,6 +1790,7 @@
 		5B8F0ED874DF8C9A51B0AB6F /* SettingsScreenCoordinator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SettingsScreenCoordinator.swift; sourceTree = "<group>"; };
 		5C1F000589F2CEE6B03ECFAB /* TimelineMediaPreviewViewModelTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineMediaPreviewViewModelTests.swift; sourceTree = "<group>"; };
 		5C7C7CFA6B2A62A685FF6CE3 /* DeveloperOptionsScreenCoordinator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DeveloperOptionsScreenCoordinator.swift; sourceTree = "<group>"; };
+		5CDE60FEE95039CCCEEEE3B0 /* TimelineMediaPreviewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineMediaPreviewController.swift; sourceTree = "<group>"; };
 		5CEEAE1BFAACD6C96B6DB731 /* PHGPostHogProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PHGPostHogProtocol.swift; sourceTree = "<group>"; };
 		5D26A086A8278D39B5756D6F /* project.yml */ = {isa = PBXFileReference; lastKnownFileType = text.yaml; path = project.yml; sourceTree = "<group>"; };
 		5D53754227CEBD06358956D7 /* PinnedEventsTimelineScreenCoordinator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PinnedEventsTimelineScreenCoordinator.swift; sourceTree = "<group>"; };
@@ -2090,6 +2089,7 @@
 		9F1DF3FFFE5ED2B8133F43A7 /* MessageComposer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MessageComposer.swift; sourceTree = "<group>"; };
 		9F40FB0A43DAECEC27C73722 /* bg */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = bg; path = bg.lproj/SAS.strings; sourceTree = "<group>"; };
 		9F85164F9475FF2867F71AAA /* RoomTimelineController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomTimelineController.swift; sourceTree = "<group>"; };
+		9FD40B92FCF20165658296AD /* TimelineMediaPreviewModifier.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineMediaPreviewModifier.swift; sourceTree = "<group>"; };
 		A00C7A331B72C0F05C00392F /* RoomScreenViewModelProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomScreenViewModelProtocol.swift; sourceTree = "<group>"; };
 		A010B8EAD1A9F6B4686DF2F4 /* BlockedUsersScreenViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = BlockedUsersScreenViewModel.swift; sourceTree = "<group>"; };
 		A019A12C866D64CF072024B9 /* AppLockSetupPINScreenViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppLockSetupPINScreenViewModel.swift; sourceTree = "<group>"; };
@@ -2134,7 +2134,6 @@
 		A9E88667D393612FD5D84718 /* fi */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = fi; path = fi.lproj/SAS.strings; sourceTree = "<group>"; };
 		A9FAFE1C2149E6AC8156ED2B /* Collection.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Collection.swift; sourceTree = "<group>"; };
 		AA19C32BD97F45847724E09A /* en */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = en; path = en.lproj/Untranslated.strings; sourceTree = "<group>"; };
-		AA57E8563C346B13DDE4A6F4 /* TimelineMediaPreviewScreen.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineMediaPreviewScreen.swift; sourceTree = "<group>"; };
 		AAC9344689121887B74877AF /* UnitTests.xctest */ = {isa = PBXFileReference; includeInIndex = 0; lastKnownFileType = wrapper.cfbundle; path = UnitTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		AACE9B8E1A4AE79A7E2914F6 /* es */ = {isa = PBXFileReference; lastKnownFileType = text.plist.stringsdict; name = es; path = es.lproj/Localizable.stringsdict; sourceTree = "<group>"; };
 		AAD01F7FC2BBAC7351948595 /* UserProfile+Mock.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UserProfile+Mock.swift"; sourceTree = "<group>"; };
@@ -2409,7 +2408,6 @@
 		E321E840DCC63790049984F4 /* ElementCallServiceMock.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ElementCallServiceMock.swift; sourceTree = "<group>"; };
 		E34685D186453E429ADEE58E /* ClientProtocolTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ClientProtocolTests.swift; sourceTree = "<group>"; };
 		E36CB905A2B9EC2C92A2DA7C /* KeychainController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = KeychainController.swift; sourceTree = "<group>"; };
-		E3A62FBD3007312311C14DD8 /* TimelineMediaPreviewCoordinator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineMediaPreviewCoordinator.swift; sourceTree = "<group>"; };
 		E3B97591B2D3D4D67553506D /* AnalyticsClientProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AnalyticsClientProtocol.swift; sourceTree = "<group>"; };
 		E4103AB4340F2974D690A12A /* CallScreen.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CallScreen.swift; sourceTree = "<group>"; };
 		E413F4CBD7BF0588F394A9DD /* RoomDetailsEditScreenViewModel.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomDetailsEditScreenViewModel.swift; sourceTree = "<group>"; };
@@ -3033,7 +3031,6 @@
 			isa = PBXGroup;
 			children = (
 				01C4C7DB37597D7D8379511A /* Assets.xcassets */,
-				17F7A723A46DF5C95BE15EBF /* clear.png */,
 				A0C06C0F6A8621B22BFAEB56 /* Localizations */,
 				8AEA6A91159FA0D3EAFCCB0D /* Sounds */,
 			);
@@ -3528,9 +3525,9 @@
 			children = (
 				638A81B97D51591D0FCFA598 /* InteractiveQuickLook.swift */,
 				E7495E1119753B06FF2C2279 /* PhotoLibraryManager.swift */,
-				E3A62FBD3007312311C14DD8 /* TimelineMediaPreviewCoordinator.swift */,
 				B18A454132A5A5247802821E /* TimelineMediaPreviewDataSource.swift */,
 				2A2BB38DF61F5100B8723112 /* TimelineMediaPreviewModels.swift */,
+				9FD40B92FCF20165658296AD /* TimelineMediaPreviewModifier.swift */,
 				53F41CEAAE2BB4E74CDC2278 /* TimelineMediaPreviewViewModel.swift */,
 				5EC4A8482DA110602FE6DF42 /* View */,
 			);
@@ -3945,10 +3942,10 @@
 		5EC4A8482DA110602FE6DF42 /* View */ = {
 			isa = PBXGroup;
 			children = (
+				5CDE60FEE95039CCCEEEE3B0 /* TimelineMediaPreviewController.swift */,
 				467498BEA681758BE2F80826 /* TimelineMediaPreviewDetailsView.swift */,
 				30856520F3263D0E195710D7 /* TimelineMediaPreviewFileExportPicker.swift */,
 				C75FE3F524B575D53787868C /* TimelineMediaPreviewRedactConfirmationView.swift */,
-				AA57E8563C346B13DDE4A6F4 /* TimelineMediaPreviewScreen.swift */,
 			);
 			path = View;
 			sourceTree = "<group>";
@@ -6354,7 +6351,6 @@
 				5FCD8AFA364206EE32B909A3 /* Settings.bundle in Resources */,
 				CE1694C7BB93C3311524EF28 /* Untranslated.strings in Resources */,
 				2797C9D9BA642370F1C85D78 /* Untranslated.stringsdict in Resources */,
-				BFDDAF1A36FBC7CF63DCB7DD /* clear.png in Resources */,
 				147597951DB07123A87AA1D1 /* landscape_test_image.jpg in Resources */,
 				FDC67E8C0EDCB00ABC66C859 /* landscape_test_video.mov in Resources */,
 				E67418DACEDBC29E988E6ACD /* message.caf in Resources */,
@@ -7569,13 +7565,13 @@
 				1B88BB631F7FC45A213BB554 /* TimelineItemSender.swift in Sources */,
 				EFBBD44C0A16F017C32D2099 /* TimelineItemStatusView.swift in Sources */,
 				562EFB9AB62B38830D9AA778 /* TimelineMediaFrame.swift in Sources */,
-				FE43747C116CA3D8D6B92F5F /* TimelineMediaPreviewCoordinator.swift in Sources */,
+				3684AD01C5FCB7616B28F629 /* TimelineMediaPreviewController.swift in Sources */,
 				2A56B00B070F83E0FE571193 /* TimelineMediaPreviewDataSource.swift in Sources */,
 				12EC6BC99F373FE5C6EB9B64 /* TimelineMediaPreviewDetailsView.swift in Sources */,
 				4ED764A24F2A715C25CF07F1 /* TimelineMediaPreviewFileExportPicker.swift in Sources */,
 				77FB08C303F4C74C0E8577E2 /* TimelineMediaPreviewModels.swift in Sources */,
+				6386EA3C898AD1A4BC1DC8A5 /* TimelineMediaPreviewModifier.swift in Sources */,
 				A32384E3D85CA65342D3A908 /* TimelineMediaPreviewRedactConfirmationView.swift in Sources */,
-				9826A4DBBEFA7041A9E0EFAD /* TimelineMediaPreviewScreen.swift in Sources */,
 				86769B62BAE17601B3AE1B60 /* TimelineMediaPreviewViewModel.swift in Sources */,
 				B818580464CFB5400A3EF6AE /* TimelineModels.swift in Sources */,
 				E82E13CC3EB923CCB8F8273C /* TimelineProxy.swift in Sources */,

ElementX/Sources/FlowCoordinators/MediaEventsTimelineFlowCoordinator.swift

@@ -95,8 +95,9 @@ class MediaEventsTimelineFlowCoordinator: FlowCoordinatorProtocol {
         coordinator.actions
             .sink { [weak self] action in
                 switch action {
-                case .viewItem(let previewContext):
+                case .viewInRoomTimeline(let itemID):
-                    self?.presentMediaPreview(for: previewContext)
+                    self?.navigationStackCoordinator.pop(animated: false)
+                    self?.actionsSubject.send(.viewInRoomTimeline(itemID))
                 }
             }
             .store(in: &cancellables)
@@ -105,27 +106,4 @@ class MediaEventsTimelineFlowCoordinator: FlowCoordinatorProtocol {
             self?.actionsSubject.send(.finished)
         }
     }
-    
-    private func presentMediaPreview(for previewContext: TimelineMediaPreviewContext) {
-        let parameters = TimelineMediaPreviewCoordinatorParameters(context: previewContext,
-                                                                   mediaProvider: userSession.mediaProvider,
-                                                                   userIndicatorController: userIndicatorController,
-                                                                   appMediator: appMediator)
-        
-        let coordinator = TimelineMediaPreviewCoordinator(parameters: parameters)
-        coordinator.actionsPublisher
-            .sink { [weak self] action in
-                switch action {
-                case .viewInRoomTimeline(let itemID):
-                    self?.navigationStackCoordinator.pop(animated: false)
-                    self?.actionsSubject.send(.viewInRoomTimeline(itemID))
-                    self?.navigationStackCoordinator.setFullScreenCoverCoordinator(nil)
-                case .dismiss:
-                    self?.navigationStackCoordinator.setFullScreenCoverCoordinator(nil)
-                }
-            }
-            .store(in: &cancellables)
-        
-        navigationStackCoordinator.setFullScreenCoverCoordinator(coordinator)
-    }
 }

ElementX/Sources/Screens/FilePreviewScreen/TimelineMediaPreviewCoordinator.swift

@@ -1,81 +0,0 @@
-//
-// Copyright 2024 New Vector Ltd.
-//
-// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-// Please see LICENSE files in the repository root for full details.
-//
-
-import Combine
-import SwiftUI
-
-struct TimelineMediaPreviewContext {
-    /// The initial item to preview from the provided timeline.
-    /// This item's `id` will be used as the navigation transition's `sourceID`.
-    let item: EventBasedMessageTimelineItemProtocol
-    /// The timeline that the preview comes from, to allow for swiping to other media.
-    let viewModel: TimelineViewModelProtocol
-    /// The namespace that the navigation transition's `sourceID` should be defined in.
-    let namespace: Namespace.ID
-    /// A closure to be called whenever a different preview item is shown. It should also
-    /// be called *after* the preview has been dismissed, with an ID of `nil`.
-    ///
-    /// This helps work around a bug caused by the flipped scrollview where the zoomed
-    /// thumbnail starts off upside down while loading the preview screen.
-    var itemIDHandler: ((TimelineItemIdentifier?) -> Void)?
-}
-
-struct TimelineMediaPreviewCoordinatorParameters {
-    let context: TimelineMediaPreviewContext
-    let mediaProvider: MediaProviderProtocol
-    let userIndicatorController: UserIndicatorControllerProtocol
-    let appMediator: AppMediatorProtocol
-}
-
-enum TimelineMediaPreviewCoordinatorAction {
-    case viewInRoomTimeline(TimelineItemIdentifier)
-    case dismiss
-}
-
-final class TimelineMediaPreviewCoordinator: CoordinatorProtocol {
-    private let parameters: TimelineMediaPreviewCoordinatorParameters
-    private let viewModel: TimelineMediaPreviewViewModel
-    
-    private var cancellables = Set<AnyCancellable>()
- 
-    private let actionsSubject: PassthroughSubject<TimelineMediaPreviewCoordinatorAction, Never> = .init()
-    var actionsPublisher: AnyPublisher<TimelineMediaPreviewCoordinatorAction, Never> {
-        actionsSubject.eraseToAnyPublisher()
-    }
-    
-    init(parameters: TimelineMediaPreviewCoordinatorParameters) {
-        self.parameters = parameters
-        
-        viewModel = TimelineMediaPreviewViewModel(context: parameters.context,
-                                                  mediaProvider: parameters.mediaProvider,
-                                                  photoLibraryManager: PhotoLibraryManager(),
-                                                  userIndicatorController: parameters.userIndicatorController,
-                                                  appMediator: parameters.appMediator)
-    }
-    
-    func start() {
-        viewModel.actions.sink { [weak self] action in
-            MXLog.info("Coordinator: received view model action: \(action)")
-            
-            guard let self else { return }
-            switch action {
-            case .viewInRoomTimeline(let itemID):
-                actionsSubject.send(.viewInRoomTimeline(itemID))
-            case .dismiss:
-                actionsSubject.send(.dismiss)
-            }
-        }
-        .store(in: &cancellables)
-    }
-        
-    func toPresentable() -> AnyView {
-        // Calling the completion onDisappear isn't ideal, but we don't push away from the screen so it should be
-        // a good enough approximation of didDismiss, given that the only other option is our navigation callbacks
-        // which are essentially willDismiss callbacks and happen too early for this particular completion handler.
-        AnyView(TimelineMediaPreviewScreen(context: viewModel.context, itemIDHandler: parameters.context.itemIDHandler))
-    }
-}

ElementX/Sources/Screens/FilePreviewScreen/TimelineMediaPreviewDataSource.swift

@@ -156,13 +156,14 @@ enum TimelineMediaPreviewItem: Equatable {
         // MARK: QLPreviewItem
         
         var previewItemURL: URL? {
-            // Falling back to a clear image allows the presentation animation to work when
+            fileHandle?.url
-            // the item is in the event cache and just needs to be loaded from the store.
-            fileHandle?.url ?? Bundle.main.url(forResource: "clear", withExtension: "png")
         }
         
         var previewItemTitle: String? {
-            filename
+            switch fileHandle?.url {
+            case .some: filename
+            case .none: " " // Don't show any background text when the preview is still loading.
+            }
         }
         
         // MARK: Event details

ElementX/Sources/Screens/FilePreviewScreen/TimelineMediaPreviewModels.swift

@@ -13,6 +13,42 @@ enum TimelineMediaPreviewViewModelAction: Equatable {
     case dismiss
 }
 
+enum TimelineMediaPreviewDriverAction {
+    case itemLoaded(TimelineItemIdentifier)
+    case showItemDetails(TimelineMediaPreviewItem.Media)
+    case exportFile(TimelineMediaPreviewFileExportPicker.File)
+    case authorizationRequired(appMediator: AppMediatorProtocol)
+    case dismissDetailsSheet
+    
+    var isItemLoaded: Bool {
+        switch self {
+        case .itemLoaded: true
+        default: false
+        }
+    }
+    
+    var isShowItemDetails: Bool {
+        switch self {
+        case .showItemDetails: true
+        default: false
+        }
+    }
+    
+    var isExportFile: Bool {
+        switch self {
+        case .exportFile: true
+        default: false
+        }
+    }
+    
+    var isAuthorizationRequired: Bool {
+        switch self {
+        case .authorizationRequired: true
+        default: false
+        }
+    }
+}
+
 struct TimelineMediaPreviewViewState: BindableState {
     /// The data source for all of the preview-able items.
     var dataSource: TimelineMediaPreviewDataSource
@@ -22,23 +58,15 @@ struct TimelineMediaPreviewViewState: BindableState {
     /// All of the available actions for the current item.
     var currentItemActions: TimelineItemMenuActions?
     
-    /// The namespace used for the zoom transition.
+    /// A publisher that the view model uses to signal actions to the QLPreviewController.
-    let transitionNamespace: Namespace.ID
+    let previewControllerDriver = PassthroughSubject<TimelineMediaPreviewDriverAction, Never>()
-    /// A publisher that the view model uses to signal to the QLPreviewController when the current item has been loaded.
-    let fileLoadedPublisher = PassthroughSubject<TimelineItemIdentifier, Never>()
     
     var bindings = TimelineMediaPreviewViewStateBindings()
 }
 
 struct TimelineMediaPreviewViewStateBindings {
-    /// A binding that will present the Details view for the specified item.
-    var mediaDetailsItem: TimelineMediaPreviewItem.Media?
     /// A binding that will present a confirmation to redact the specified item.
     var redactConfirmationItem: TimelineMediaPreviewItem.Media?
-    /// A binding that will present a document picker to export the specified file.
-    var fileToExport: TimelineMediaPreviewFileExportPicker.File?
-    
-    var alertInfo: AlertInfo<TimelineMediaPreviewAlertType>?
 }
 
 enum TimelineMediaPreviewAlertType {
@@ -51,5 +79,4 @@ enum TimelineMediaPreviewViewAction {
     case menuAction(TimelineItemMenuAction, item: TimelineMediaPreviewItem.Media)
     case redactConfirmation(item: TimelineMediaPreviewItem.Media)
     case timelineEndReached
-    case dismiss
 }

ElementX/Sources/Screens/FilePreviewScreen/TimelineMediaPreviewModifier.swift

@@ -0,0 +1,188 @@
+//
+// Copyright 2022-2024 New Vector Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Combine
+import QuickLook
+import SwiftUI
+
+extension View {
+    /// Preview a media file using a QuickLook Preview Controller. The preview is interactive with
+    /// the dismiss gesture working as expected if it was presented from UIKit.
+    func timelineMediaPreview(viewModel: Binding<TimelineMediaPreviewViewModel?>) -> some View {
+        modifier(TimelineMediaPreviewModifier(viewModel: viewModel))
+    }
+}
+
+private struct TimelineMediaPreviewModifier: ViewModifier {
+    @Binding var viewModel: TimelineMediaPreviewViewModel?
+    
+    @State private var dismissalPublisher = PassthroughSubject<Void, Never>()
+    
+    func body(content: Content) -> some View {
+        content.background {
+            if let viewModel {
+                MediaPreviewViewController(viewModel: viewModel,
+                                           dismissalPublisher: dismissalPublisher) { self.viewModel = nil }
+                    .id(viewModel.instanceID) // Fixes a bug where opening a second preview too quickly can break presentation.
+            } else {
+                // Work around QLPreviewController dismissal issues, see below.
+                let _ = dismissalPublisher.send(())
+            }
+        }
+    }
+}
+
+private struct MediaPreviewViewController: UIViewControllerRepresentable {
+    let viewModel: TimelineMediaPreviewViewModel
+    let dismissalPublisher: PassthroughSubject<Void, Never>
+    let onDismiss: () -> Void
+
+    func makeUIViewController(context: Context) -> PreviewHostingController {
+        PreviewHostingController(viewModel: viewModel,
+                                 dismissalPublisher: dismissalPublisher,
+                                 onDismiss: onDismiss)
+    }
+
+    func updateUIViewController(_ uiViewController: PreviewHostingController, context: Context) { }
+    
+    /// A view controller that hosts the QuickLook preview.
+    ///
+    /// This wrapper somehow allows the preview controller to do presentation/dismissal
+    /// animations and interactions which don't work if you represent it directly to SwiftUI 🤷‍♂️
+    class PreviewHostingController: UIViewController, QLPreviewControllerDelegate {
+        let onDismiss: () -> Void
+        let sourceView = UIView()
+        
+        private let previewController: TimelineMediaPreviewController
+        private var hasBeenPresented = false
+        
+        private var dismissalObserver: AnyCancellable?
+        private var cancellables: Set<AnyCancellable> = []
+        
+        init(viewModel: TimelineMediaPreviewViewModel,
+             dismissalPublisher: PassthroughSubject<Void, Never>,
+             onDismiss: @escaping () -> Void) {
+            self.onDismiss = onDismiss
+            previewController = TimelineMediaPreviewController(context: viewModel.context)
+
+            super.init(nibName: nil, bundle: nil)
+            
+            // The QLPreviewController will not automatically dismiss itself when the underlying view is removed
+            // (e.g. switching rooms from a notification) and it continues to hold on to the whole hierarcy.
+            // Manually tell it to dismiss itself here.
+            dismissalObserver = dismissalPublisher.sink { [weak self] _ in
+                // Dispatching on main.async with weak self we avoid doing an extra dismiss if the view is presented on top of another modal
+                DispatchQueue.main.async { [weak self] in
+                    self?.dismiss(animated: true)
+                }
+            }
+        }
+        
+        @available(*, unavailable)
+        required init?(coder: NSCoder) {
+            fatalError("init(coder:) has not been implemented")
+        }
+        
+        override func viewDidLoad() {
+            view.backgroundColor = .clear
+            view.addSubview(sourceView)
+            
+            sourceView.translatesAutoresizingMaskIntoConstraints = false
+            NSLayoutConstraint.activate([
+                sourceView.centerXAnchor.constraint(equalTo: view.centerXAnchor),
+                sourceView.centerYAnchor.constraint(equalTo: view.bottomAnchor),
+                sourceView.widthAnchor.constraint(equalToConstant: 100),
+                sourceView.heightAnchor.constraint(equalToConstant: 100)
+            ])
+        }
+        
+        // Don't use viewWillAppear due to the following warning:
+        // Presenting view controller <QLPreviewController> from detached view controller <HostingController> is not supported,
+        // and may result in incorrect safe area insets and a corrupt root presentation. Make sure <HostingController> is in
+        // the view controller hierarchy before presenting from it. Will become a hard exception in a future release.
+        override func viewDidAppear(_ animated: Bool) {
+            super.viewDidAppear(animated)
+            
+            guard !hasBeenPresented else { return }
+            
+            previewController.delegate = self
+            
+            present(previewController, animated: true)
+            
+            hasBeenPresented = true
+        }
+        
+        // MARK: QLPreviewControllerDelegate
+        
+        func previewController(_ controller: QLPreviewController, editingModeFor previewItem: QLPreviewItem) -> QLPreviewItemEditingMode {
+            .disabled
+        }
+        
+        func previewController(_ controller: QLPreviewController, transitionViewFor item: any QLPreviewItem) -> UIView? {
+            sourceView
+        }
+        
+        func previewControllerDidDismiss(_ controller: QLPreviewController) {
+            onDismiss()
+        }
+    }
+}
+
+// MARK: - Previews
+
+struct TimelineMediaPreviewModifier_Previews: PreviewProvider {
+    static let viewModel = makeViewModel()
+    static let downloadingViewModel = makeViewModel(isDownloading: true)
+    static let downloadErrorViewModel = makeViewModel(isDownloadError: true)
+    
+    static var previews: some View {
+        MediaPreviewViewController(viewModel: viewModel, dismissalPublisher: .init()) { }
+            .previewDisplayName("Normal")
+        MediaPreviewViewController(viewModel: downloadingViewModel, dismissalPublisher: .init()) { }
+            .previewDisplayName("Downloading")
+        MediaPreviewViewController(viewModel: downloadErrorViewModel, dismissalPublisher: .init()) { }
+            .previewDisplayName("Download Error")
+    }
+    
+    static func makeViewModel(isDownloading: Bool = false, isDownloadError: Bool = false) -> TimelineMediaPreviewViewModel {
+        let item = FileRoomTimelineItem(id: .randomEvent,
+                                        timestamp: .mock,
+                                        isOutgoing: false,
+                                        isEditable: false,
+                                        canBeRepliedTo: true,
+                                        isThreaded: false,
+                                        sender: .init(id: "", displayName: "Sally Sanderson"),
+                                        content: .init(filename: "Important document.pdf",
+                                                       caption: "A caption goes right here.",
+                                                       source: try? .init(url: .mockMXCFile, mimeType: nil),
+                                                       fileSize: 3 * 1024 * 1024,
+                                                       thumbnailSource: nil,
+                                                       contentType: .pdf))
+        
+        let timelineController = MockRoomTimelineController(timelineKind: .media(.mediaFilesScreen))
+        timelineController.timelineItems = [item]
+        
+        let mediaProvider = MediaProviderMock(configuration: .init())
+        
+        if isDownloading {
+            mediaProvider.loadFileFromSourceFilenameClosure = { _, _ in
+                try? await Task.sleep(for: .seconds(3600))
+                return .failure(.failedRetrievingFile)
+            }
+        } else if isDownloadError {
+            mediaProvider.loadFileFromSourceFilenameClosure = { _, _ in .failure(.failedRetrievingFile) }
+        }
+        
+        return TimelineMediaPreviewViewModel(initialItem: item,
+                                             timelineViewModel: TimelineViewModel.mock(timelineKind: timelineController.timelineKind,
+                                                                                       timelineController: timelineController),
+                                             mediaProvider: mediaProvider,
+                                             photoLibraryManager: PhotoLibraryManagerMock(.init()),
+                                             userIndicatorController: UserIndicatorControllerMock(),
+                                             appMediator: AppMediatorMock())
+    }
+}

ElementX/Sources/Screens/FilePreviewScreen/TimelineMediaPreviewViewModel.swift

@@ -11,8 +11,9 @@ import Foundation
 typealias TimelineMediaPreviewViewModelType = StateStoreViewModel<TimelineMediaPreviewViewState, TimelineMediaPreviewViewAction>
 
 class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
+    let instanceID = UUID()
+    
     private let timelineViewModel: TimelineViewModelProtocol
-    private let currentItemIDHandler: ((TimelineItemIdentifier?) -> Void)?
     private let mediaProvider: MediaProviderProtocol
     private let photoLibraryManager: PhotoLibraryManagerProtocol
     private let userIndicatorController: UserIndicatorControllerProtocol
@@ -23,13 +24,13 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
         actionsSubject.eraseToAnyPublisher()
     }
     
-    init(context: TimelineMediaPreviewContext,
+    init(initialItem: EventBasedMessageTimelineItemProtocol,
+         timelineViewModel: TimelineViewModelProtocol,
          mediaProvider: MediaProviderProtocol,
          photoLibraryManager: PhotoLibraryManagerProtocol,
          userIndicatorController: UserIndicatorControllerProtocol,
          appMediator: AppMediatorProtocol) {
-        timelineViewModel = context.viewModel
+        self.timelineViewModel = timelineViewModel
-        currentItemIDHandler = context.itemIDHandler
         self.mediaProvider = mediaProvider
         self.photoLibraryManager = photoLibraryManager
         self.userIndicatorController = userIndicatorController
@@ -38,9 +39,8 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
         let timelineState = timelineViewModel.context.viewState.timelineState
         
         super.init(initialViewState: TimelineMediaPreviewViewState(dataSource: .init(itemViewStates: timelineState.itemViewStates,
-                                                                                     initialItem: context.item,
+                                                                                     initialItem: initialItem,
-                                                                                     paginationState: timelineState.paginationState),
+                                                                                     paginationState: timelineState.paginationState)),
-                                                                   transitionNamespace: context.namespace),
                    mediaProvider: mediaProvider)
         
         rebuildCurrentItemActions()
@@ -72,10 +72,11 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
         case .updateCurrentItem(let item):
             Task { await updateCurrentItem(item) }
         case .showItemDetails(let mediaItem):
-            state.bindings.mediaDetailsItem = mediaItem
+            state.previewControllerDriver.send(.showItemDetails(mediaItem))
         case .menuAction(let action, let item):
             switch action {
             case .viewInRoomTimeline:
+                state.previewControllerDriver.send(.dismissDetailsSheet)
                 actionsSubject.send(.viewInRoomTimeline(item.id))
             case .save:
                 Task { await saveCurrentItem() }
@@ -88,8 +89,6 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
             redactItem(item)
         case .timelineEndReached:
             showTimelineEndIndicator()
-        case .dismiss:
-            actionsSubject.send(.dismiss)
         }
     }
     
@@ -101,13 +100,11 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
         rebuildCurrentItemActions()
         
         if case let .media(mediaItem) = previewItem {
-            currentItemIDHandler?(mediaItem.id)
-            
             if mediaItem.fileHandle == nil, let source = mediaItem.mediaSource {
                 switch await mediaProvider.loadFileFromSource(source, filename: mediaItem.filename) {
                 case .success(let handle):
                     mediaItem.fileHandle = handle
-                    state.fileLoadedPublisher.send(mediaItem.id)
+                    state.previewControllerDriver.send(.itemLoaded(mediaItem.id))
                 case .failure(let error):
                     MXLog.error("Failed loading media: \(error)")
                     context.objectWillChange.send() // Manually trigger the SwiftUI view update.
@@ -143,12 +140,12 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
         }
         
         // Dismiss the details sheet (nicer flow for images/video but _required_ in order to select a file directory).
-        state.bindings.mediaDetailsItem = nil
+        state.previewControllerDriver.send(.dismissDetailsSheet)
         
         do {
             switch mediaItem.timelineItem {
             case is AudioRoomTimelineItem, is FileRoomTimelineItem:
-                state.bindings.fileToExport = .init(url: fileURL)
+                state.previewControllerDriver.send(.exportFile(.init(url: fileURL)))
                 return // Don't show the indicator.
             case is ImageRoomTimelineItem:
                 try await photoLibraryManager.addResource(.photo, at: fileURL).get()
@@ -161,10 +158,7 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
             showSavedIndicator()
         } catch PhotoLibraryManagerError.notAuthorized {
             MXLog.error("Not authorised to save item to photo library")
-            state.bindings.alertInfo = .init(id: .authorizationRequired,
+            state.previewControllerDriver.send(.authorizationRequired(appMediator: appMediator))
-                                             title: L10n.dialogPermissionPhotoLibraryTitleIos(InfoPlistReader.main.bundleDisplayName),
-                                             primaryButton: .init(title: L10n.commonSettings) { self.appMediator.openAppSettings() },
-                                             secondaryButton: .init(title: L10n.actionCancel, role: .cancel, action: nil))
         } catch {
             MXLog.error("Failed saving item: \(error)")
             showErrorIndicator()
@@ -174,7 +168,7 @@ class TimelineMediaPreviewViewModel: TimelineMediaPreviewViewModelType {
     private func redactItem(_ item: TimelineMediaPreviewItem.Media) {
         timelineViewModel.context.send(viewAction: .handleTimelineItemMenuAction(itemID: item.id, action: .redact))
         state.bindings.redactConfirmationItem = nil
-        state.bindings.mediaDetailsItem = nil
+        state.previewControllerDriver.send(.dismissDetailsSheet)
         actionsSubject.send(.dismiss)
         showRedactedIndicator()
     }

ElementX/Sources/Screens/FilePreviewScreen/View/TimelineMediaPreviewController.swift

@@ -0,0 +1,342 @@
+//
+// Copyright 2022-2024 New Vector Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
+// Please see LICENSE files in the repository root for full details.
+//
+
+import Combine
+import Compound
+import QuickLook
+import SwiftUI
+
+class TimelineMediaPreviewController: QLPreviewController {
+    private let context: TimelineMediaPreviewViewModel.Context
+    
+    private let headerHostingController: UIHostingController<HeaderView>
+    private let detailsButtonHostingController: UIHostingController<DetailsButton>
+    private let captionHostingController: UIHostingController<CaptionView>
+    private let downloadIndicatorHostingController: UIHostingController<DownloadIndicatorView>
+    private var detailsHostingController: UIHostingController<TimelineMediaPreviewDetailsView>?
+    
+    private var barButtonTimer: Timer?
+    
+    private var cancellables: Set<AnyCancellable> = []
+    
+    private var navigationBar: UINavigationBar? { view.subviews.first?.subviews.first { $0 is UINavigationBar } as? UINavigationBar }
+    private var toolbar: UIToolbar? { view.subviews.first?.subviews.last { $0 is UIToolbar } as? UIToolbar }
+    private var captionView: UIView { captionHostingController.view }
+    
+    override var overrideUserInterfaceStyle: UIUserInterfaceStyle {
+        get { .dark }
+        set { }
+    }
+    
+    init(context: TimelineMediaPreviewViewModel.Context) {
+        self.context = context
+        
+        headerHostingController = UIHostingController(rootView: HeaderView(context: context))
+        headerHostingController.view.backgroundColor = .clear
+        headerHostingController.sizingOptions = .intrinsicContentSize
+        detailsButtonHostingController = UIHostingController(rootView: DetailsButton(context: context))
+        detailsButtonHostingController.view.backgroundColor = .clear
+        detailsButtonHostingController.sizingOptions = .intrinsicContentSize
+        captionHostingController = UIHostingController(rootView: CaptionView(context: context))
+        captionHostingController.view.backgroundColor = .clear
+        captionHostingController.sizingOptions = .intrinsicContentSize
+        downloadIndicatorHostingController = UIHostingController(rootView: DownloadIndicatorView(context: context))
+        downloadIndicatorHostingController.view.backgroundColor = .clear
+        downloadIndicatorHostingController.sizingOptions = .intrinsicContentSize
+        
+        super.init(nibName: nil, bundle: nil)
+        
+        view.addSubview(captionView)
+        // Constraints added later as the toolbar isn't available yet.
+        
+        view.addSubview(downloadIndicatorHostingController.view)
+        downloadIndicatorHostingController.view.translatesAutoresizingMaskIntoConstraints = false
+        NSLayoutConstraint.activate([
+            downloadIndicatorHostingController.view.centerXAnchor.constraint(equalTo: view.centerXAnchor),
+            downloadIndicatorHostingController.view.centerYAnchor.constraint(equalTo: view.centerYAnchor)
+        ])
+        
+        // Observation of currentPreviewItem doesn't work, so use the index instead.
+        publisher(for: \.currentPreviewItemIndex)
+            .sink { [weak self] _ in
+                // This isn't removing duplicates which may try to download and/or write to disk concurrently????
+                self?.loadCurrentItem()
+            }
+            .store(in: &cancellables)
+        
+        context.viewState.dataSource.previewItemsPaginationPublisher
+            .sink { [weak self] in
+                self?.handleUpdatedItems()
+            }
+            .store(in: &cancellables)
+        
+        context.viewState.previewControllerDriver
+            .sink { [weak self] action in
+                switch action {
+                case .itemLoaded(let itemID):
+                    self?.handleFileLoaded(itemID: itemID)
+                case .showItemDetails(let mediaItem):
+                    self?.presentMediaDetails(for: mediaItem)
+                case .exportFile(let file):
+                    self?.exportFile(file)
+                case .authorizationRequired(let appMediator):
+                    self?.presentAuthorizationRequiredAlert(appMediator: appMediator)
+                case .dismissDetailsSheet:
+                    self?.dismiss(animated: true)
+                }
+            }
+            .store(in: &cancellables)
+        
+        dataSource = context.viewState.dataSource
+        currentPreviewItemIndex = context.viewState.dataSource.initialItemIndex
+    }
+    
+    @available(*, unavailable) required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    // MARK: Layout
+    
+    override func viewWillLayoutSubviews() {
+        super.viewWillLayoutSubviews()
+        
+        if let toolbar {
+            // Using the toolbar's visibility doesn't work so check its frame.
+            captionView.isHidden = toolbar.frame.minY >= view.frame.maxY
+            
+            if captionView.constraints.isEmpty {
+                captionHostingController.view.translatesAutoresizingMaskIntoConstraints = false
+                NSLayoutConstraint.activate([
+                    captionView.bottomAnchor.constraint(equalTo: toolbar.topAnchor),
+                    captionView.leadingAnchor.constraint(equalTo: toolbar.leadingAnchor),
+                    captionView.trailingAnchor.constraint(equalTo: toolbar.trailingAnchor)
+                ])
+            }
+        }
+        
+        navigationBar?.topItem?.titleView = headerHostingController.view
+        
+        updateBarButtons()
+        
+        // Ridiculous hack to undo the controller's attempt to replace our info button with the list button.
+        if barButtonTimer == nil {
+            barButtonTimer = Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak self] _ in
+                self?.updateBarButtons()
+            }
+        }
+    }
+    
+    override func viewWillDisappear(_ animated: Bool) {
+        barButtonTimer?.invalidate()
+        barButtonTimer = nil
+    }
+    
+    private func updateBarButtons() {
+        guard let topItem = navigationBar?.topItem else { return }
+        
+        if topItem.leftBarButtonItem?.customView == nil {
+            let button = UIBarButtonItem(customView: detailsButtonHostingController.view)
+            navigationBar?.topItem?.leftBarButtonItem = button
+        }
+    }
+    
+    // MARK: Item loading
+    
+    private func loadCurrentItem() {
+        headerHostingController.view.sizeToFit() // Resizing isn't automatic in the toolbar 😒
+        
+        if let previewItem = currentPreviewItem as? TimelineMediaPreviewItem.Media {
+            context.send(viewAction: .updateCurrentItem(.media(previewItem)))
+        } else if let loadingItem = currentPreviewItem as? TimelineMediaPreviewItem.Loading {
+            switch loadingItem.state {
+            case .paginating:
+                context.send(viewAction: .updateCurrentItem(.loading(loadingItem)))
+            case .timelineStart:
+                Task { await returnToIndex(context.viewState.dataSource.firstPreviewItemIndex) }
+            case .timelineEnd:
+                Task { await returnToIndex(context.viewState.dataSource.lastPreviewItemIndex) }
+            }
+        } else {
+            MXLog.error("Unexpected preview item type: \(type(of: currentPreviewItem))")
+        }
+    }
+    
+    private func returnToIndex(_ index: Int) async {
+        // Sleep to fix a bug where the update didn't take effect when the swipe velocity was slow.
+        try? await Task.sleep(for: .seconds(0.1))
+        
+        currentPreviewItemIndex = index
+        context.send(viewAction: .timelineEndReached)
+    }
+    
+    private func handleUpdatedItems() {
+        if currentPreviewItem is TimelineMediaPreviewItem.Loading {
+            let dataSource = context.viewState.dataSource
+            if dataSource.previewController(self, previewItemAt: currentPreviewItemIndex) is TimelineMediaPreviewItem.Media {
+                refreshCurrentPreviewItem() // This will trigger loadCurrentItem automatically.
+            }
+        }
+    }
+    
+    private func handleFileLoaded(itemID: TimelineItemIdentifier) {
+        guard (currentPreviewItem as? TimelineMediaPreviewItem.Media)?.id == itemID else { return }
+        refreshCurrentPreviewItem()
+    }
+    
+    // MARK: - Actions
+    
+    private func presentMediaDetails(for mediaItem: TimelineMediaPreviewItem.Media) {
+        let safeArea = view.safeAreaInsets.bottom
+        let sheetHeightBinding = Binding { safeArea } set: { [weak self] newValue, _ in
+            self?.detailsHostingController?.sheetPresentationController?.detents = [.height(newValue + safeArea)]
+        }
+        
+        let hostingController = UIHostingController(rootView: TimelineMediaPreviewDetailsView(item: mediaItem,
+                                                                                              context: context,
+                                                                                              sheetHeight: sheetHeightBinding))
+        hostingController.view.backgroundColor = .compound.bgCanvasDefault
+        hostingController.overrideUserInterfaceStyle = .dark
+        hostingController.sheetPresentationController?.detents = [.height(safeArea)]
+        hostingController.sheetPresentationController?.prefersGrabberVisible = true
+        
+        present(hostingController, animated: true)
+        
+        detailsHostingController = hostingController
+    }
+    
+    private func exportFile(_ file: TimelineMediaPreviewFileExportPicker.File) {
+        let hostingController = UIHostingController(rootView: TimelineMediaPreviewFileExportPicker(file: file))
+        present(hostingController, animated: true)
+    }
+    
+    private func presentAuthorizationRequiredAlert(appMediator: AppMediatorProtocol) {
+        let alertController = UIAlertController(title: L10n.dialogPermissionPhotoLibraryTitleIos(InfoPlistReader.main.bundleDisplayName),
+                                                message: nil,
+                                                preferredStyle: .alert)
+        alertController.addAction(.init(title: L10n.commonSettings, style: .default) { _ in appMediator.openAppSettings() })
+        alertController.addAction(.init(title: L10n.actionCancel, style: .cancel))
+        
+        present(alertController, animated: true)
+    }
+}
+
+// MARK: - Subviews
+
+private struct HeaderView: View {
+    @ObservedObject var context: TimelineMediaPreviewViewModel.Context
+    private var currentItem: TimelineMediaPreviewItem { context.viewState.currentItem }
+    
+    var body: some View {
+        switch currentItem {
+        case .media(let mediaItem):
+            VStack(spacing: 0) {
+                Text(mediaItem.sender.displayName ?? mediaItem.sender.id)
+                    .font(.compound.bodySMSemibold)
+                    .foregroundStyle(.compound.textPrimary)
+                Text(mediaItem.timestamp.formatted(date: .abbreviated, time: .omitted))
+                    .font(.compound.bodyXS)
+                    .foregroundStyle(.compound.textPrimary)
+                    .textCase(.uppercase)
+            }
+            .fixedSize(horizontal: true, vertical: false)
+        case .loading:
+            Text(L10n.commonLoadingMore)
+                .font(.compound.bodySMSemibold)
+                .foregroundStyle(.compound.textPrimary)
+                .fixedSize(horizontal: true, vertical: false)
+        }
+    }
+}
+
+private struct DetailsButton: View {
+    @ObservedObject var context: TimelineMediaPreviewViewModel.Context
+    private var currentItem: TimelineMediaPreviewItem { context.viewState.currentItem }
+    
+    var isHidden: Bool {
+        switch currentItem {
+        case .media: false
+        case .loading: true
+        }
+    }
+    
+    var body: some View {
+        if case .media(let mediaItem) = currentItem {
+            Button { context.send(viewAction: .showItemDetails(mediaItem)) } label: {
+                CompoundIcon(\.info)
+            }
+        }
+    }
+}
+
+private struct CaptionView: View {
+    @ObservedObject var context: TimelineMediaPreviewViewModel.Context
+    private var currentItem: TimelineMediaPreviewItem { context.viewState.currentItem }
+    
+    var body: some View {
+        if case let .media(mediaItem) = currentItem, let caption = mediaItem.caption {
+            Text(caption)
+                .font(.compound.bodyLG)
+                .foregroundStyle(.compound.textPrimary)
+                .lineLimit(5)
+                .frame(maxWidth: .infinity, alignment: .leading)
+                .fixedSize(horizontal: false, vertical: true)
+                .padding(16)
+                .background {
+                    BlurEffectView(style: .systemChromeMaterial) // Darkest material available, matches the bottom bar when content is beneath.
+                        .ignoresSafeArea()
+                }
+                .transition(.move(edge: .bottom).combined(with: .opacity))
+        }
+    }
+}
+
+private struct DownloadIndicatorView: View {
+    @ObservedObject var context: TimelineMediaPreviewViewModel.Context
+    private var currentItem: TimelineMediaPreviewItem { context.viewState.currentItem }
+    
+    private var shouldShowDownloadIndicator: Bool {
+        switch currentItem {
+        case .media(let mediaItem): mediaItem.fileHandle == nil
+        case .loading(let loadingItem): loadingItem.state == .paginating
+        }
+    }
+    
+    var body: some View {
+        if case let .media(mediaItem) = currentItem, mediaItem.downloadError != nil {
+            VStack(spacing: 24) {
+                CompoundIcon(\.error, size: .custom(48), relativeTo: .compound.headingLG)
+                    .foregroundStyle(.compound.iconCriticalPrimary)
+                    .padding(.vertical, 24.5)
+                    .padding(.horizontal, 28.5)
+                
+                VStack(spacing: 2) {
+                    Text(L10n.commonDownloadFailed)
+                        .font(.compound.headingMDBold)
+                        .foregroundStyle(.compound.textPrimary)
+                        .multilineTextAlignment(.center)
+                    Text(L10n.screenMediaBrowserDownloadErrorMessage)
+                        .font(.compound.bodyMD)
+                        .foregroundStyle(.compound.textPrimary)
+                        .multilineTextAlignment(.center)
+                }
+            }
+            .padding(.horizontal, 24)
+            .padding(.vertical, 40)
+            .background(.compound.bgSubtlePrimary, in: RoundedRectangle(cornerRadius: 14))
+        } else if shouldShowDownloadIndicator {
+            ProgressView()
+                .controlSize(.large)
+                .tint(.compound.iconPrimary)
+        }
+    }
+}
+
+private extension UISheetPresentationController.Detent {
+    static func height(_ height: CGFloat) -> UISheetPresentationController.Detent {
+        .custom { _ in height }
+    }
+}

ElementX/Sources/Screens/FilePreviewScreen/View/TimelineMediaPreviewDetailsView.swift

@@ -12,7 +12,7 @@ struct TimelineMediaPreviewDetailsView: View {
     let item: TimelineMediaPreviewItem.Media
     @ObservedObject var context: TimelineMediaPreviewViewModel.Context
     
-    @State private var sheetHeight: CGFloat = .zero
+    @Binding var sheetHeight: CGFloat
     private let topPadding: CGFloat = 19
     
     var body: some View {
@@ -169,16 +169,16 @@ struct TimelineMediaPreviewDetailsView: View {
 import UniformTypeIdentifiers
 
 struct TimelineMediaPreviewDetailsView_Previews: PreviewProvider, TestablePreview {
-    @Namespace private static var previewNamespace
-    
     static let viewModel = makeViewModel(contentType: .jpeg, isOutgoing: true)
     static let loadingViewModel = makeViewModel(contentType: .jpeg, isOutgoing: true, isDownloaded: false)
     static let unknownTypeViewModel = makeViewModel()
     static let presentedOnRoomViewModel = makeViewModel(isPresentedOnRoomScreen: true)
     
+    @State static var sheetHeight: CGFloat = .zero
+    
     static var previews: some View {
         if case let .media(mediaItem) = viewModel.state.currentItem {
-            TimelineMediaPreviewDetailsView(item: mediaItem, context: viewModel.context)
+            TimelineMediaPreviewDetailsView(item: mediaItem, context: viewModel.context, sheetHeight: $sheetHeight)
                 .previewDisplayName("Image")
                 .snapshotPreferences(expect: viewModel.context.$viewState.map { state in
                     state.currentItemActions?.secondaryActions.contains(.redact) ?? false
@@ -186,7 +186,7 @@ struct TimelineMediaPreviewDetailsView_Previews: PreviewProvider, TestablePrevie
         }
         
         if case let .media(mediaItem) = loadingViewModel.state.currentItem {
-            TimelineMediaPreviewDetailsView(item: mediaItem, context: loadingViewModel.context)
+            TimelineMediaPreviewDetailsView(item: mediaItem, context: loadingViewModel.context, sheetHeight: $sheetHeight)
                 .previewDisplayName("Loading")
                 .snapshotPreferences(expect: loadingViewModel.context.$viewState.map { state in
                     state.currentItemActions?.secondaryActions.contains(.redact) ?? false
@@ -194,12 +194,12 @@ struct TimelineMediaPreviewDetailsView_Previews: PreviewProvider, TestablePrevie
         }
         
         if case let .media(mediaItem) = unknownTypeViewModel.state.currentItem {
-            TimelineMediaPreviewDetailsView(item: mediaItem, context: unknownTypeViewModel.context)
+            TimelineMediaPreviewDetailsView(item: mediaItem, context: unknownTypeViewModel.context, sheetHeight: $sheetHeight)
                 .previewDisplayName("Unknown type")
         }
         
         if case let .media(mediaItem) = presentedOnRoomViewModel.state.currentItem {
-            TimelineMediaPreviewDetailsView(item: mediaItem, context: presentedOnRoomViewModel.context)
+            TimelineMediaPreviewDetailsView(item: mediaItem, context: presentedOnRoomViewModel.context, sheetHeight: $sheetHeight)
                 .previewDisplayName("Incoming on Room")
         }
     }
@@ -226,10 +226,9 @@ struct TimelineMediaPreviewDetailsView_Previews: PreviewProvider, TestablePrevie
         let timelineController = MockRoomTimelineController(timelineKind: timelineKind)
         timelineController.timelineItems = [item]
         
-        let viewModel = TimelineMediaPreviewViewModel(context: .init(item: item,
+        let viewModel = TimelineMediaPreviewViewModel(initialItem: item,
-                                                                     viewModel: TimelineViewModel.mock(timelineKind: timelineKind,
+                                                      timelineViewModel: TimelineViewModel.mock(timelineKind: timelineKind,
-                                                                                                       timelineController: timelineController),
+                                                                                                timelineController: timelineController),
-                                                                     namespace: previewNamespace),
                                                       mediaProvider: MediaProviderMock(configuration: .init()),
                                                       photoLibraryManager: PhotoLibraryManagerMock(.init()),
                                                       userIndicatorController: UserIndicatorControllerMock(),

ElementX/Sources/Screens/FilePreviewScreen/View/TimelineMediaPreviewRedactConfirmationView.swift

@@ -121,7 +121,6 @@ struct TimelineMediaPreviewRedactConfirmationView: View {
 import UniformTypeIdentifiers
 
 struct TimelineMediaPreviewRedactConfirmationView_Previews: PreviewProvider, TestablePreview {
-    @Namespace private static var previewNamespace
     static let viewModel = makeViewModel(contentType: .jpeg)
     
     static var previews: some View {
@@ -147,10 +146,9 @@ struct TimelineMediaPreviewRedactConfirmationView_Previews: PreviewProvider, Tes
         
         let timelineController = MockRoomTimelineController(timelineKind: .media(.mediaFilesScreen))
         timelineController.timelineItems = [item]
-        return TimelineMediaPreviewViewModel(context: .init(item: item,
+        return TimelineMediaPreviewViewModel(initialItem: item,
-                                                            viewModel: TimelineViewModel.mock(timelineKind: timelineController.timelineKind,
+                                             timelineViewModel: TimelineViewModel.mock(timelineKind: timelineController.timelineKind,
-                                                                                              timelineController: timelineController),
+                                                                                       timelineController: timelineController),
-                                                            namespace: previewNamespace),
                                              mediaProvider: MediaProviderMock(configuration: .init()),
                                              photoLibraryManager: PhotoLibraryManagerMock(.init()),
                                              userIndicatorController: UserIndicatorControllerMock(),

ElementX/Sources/Screens/FilePreviewScreen/View/TimelineMediaPreviewScreen.swift

@@ -1,326 +0,0 @@
-//
-// Copyright 2022-2024 New Vector Ltd.
-//
-// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
-// Please see LICENSE files in the repository root for full details.
-//
-
-import Combine
-import Compound
-import QuickLook
-import SwiftUI
-
-struct TimelineMediaPreviewScreen: View {
-    @ObservedObject var context: TimelineMediaPreviewViewModel.Context
-    var itemIDHandler: ((TimelineItemIdentifier?) -> Void)?
-    
-    @State private var isFullScreen = false
-    private var toolbarVisibility: Visibility { isFullScreen ? .hidden : .visible }
-    
-    private var currentItem: TimelineMediaPreviewItem { context.viewState.currentItem }
-    private var currentItemID: TimelineItemIdentifier? {
-        guard case .media(let mediaItem) = currentItem else { return nil }
-        return mediaItem.id
-    }
-    
-    private var shouldShowDownloadIndicator: Bool {
-        switch currentItem {
-        case .media(let mediaItem): mediaItem.fileHandle == nil
-        case .loading(let loadingItem): loadingItem.state == .paginating
-        }
-    }
-    
-    var body: some View {
-        NavigationStack {
-            quickLookPreview
-        }
-        .introspect(.navigationStack, on: .supportedVersions) {
-            // Fixes a bug where the QuickLook view overrides the .toolbarBackground(.visible) after it loads the real item.
-            $0.navigationBar.scrollEdgeAppearance = $0.navigationBar.standardAppearance
-            $0.toolbar.scrollEdgeAppearance = $0.toolbar.standardAppearance
-        }
-        .sheet(item: $context.mediaDetailsItem) { item in
-            TimelineMediaPreviewDetailsView(item: item, context: context)
-        }
-        .sheet(item: $context.fileToExport) { file in
-            TimelineMediaPreviewFileExportPicker(file: file)
-                .preferredColorScheme(.dark)
-        }
-        .alert(item: $context.alertInfo)
-        .preferredColorScheme(.dark)
-        .onDisappear {
-            itemIDHandler?(nil)
-        }
-        .zoomTransition(sourceID: currentItemID, in: context.viewState.transitionNamespace)
-    }
-    
-    var quickLookPreview: some View {
-        Color.clear // A completely clear view breaks any SwiftUI gestures (such as drag to dismiss).
-            .background { QuickLookView(viewModelContext: context).ignoresSafeArea() } // Not the root view to stop QL hijacking the toolbar.
-            .overlay(alignment: .topTrailing) { fullScreenButton }
-            .overlay { downloadStatusIndicator }
-            .toolbar { toolbar }
-            .toolbar(toolbarVisibility, for: .navigationBar)
-            .toolbarBackground(.visible, for: .navigationBar) // The toolbar's scrollEdgeAppearance isn't aware of the quicklook view 🤷‍♂️
-            .navigationBarTitleDisplayMode(.inline)
-            .safeAreaInset(edge: .bottom, spacing: 0) { caption }
-    }
-    
-    @ViewBuilder
-    private var fullScreenButton: some View {
-        if case .media = currentItem {
-            Button {
-                withAnimation { isFullScreen.toggle() }
-            } label: {
-                CompoundIcon(isFullScreen ? \.collapse : \.expand, size: .xSmall, relativeTo: .compound.bodyLG)
-                    .padding(6)
-                    .background(.thinMaterial, in: Circle())
-            }
-            .tint(.compound.textActionPrimary)
-            .padding(.top, 12)
-            .padding(.trailing, 14)
-        }
-    }
-    
-    @ViewBuilder
-    private var downloadStatusIndicator: some View {
-        if case let .media(mediaItem) = currentItem, mediaItem.downloadError != nil {
-            VStack(spacing: 24) {
-                CompoundIcon(\.error, size: .custom(48), relativeTo: .compound.headingLG)
-                    .foregroundStyle(.compound.iconCriticalPrimary)
-                    .padding(.vertical, 24.5)
-                    .padding(.horizontal, 28.5)
-                
-                VStack(spacing: 2) {
-                    Text(L10n.commonDownloadFailed)
-                        .font(.compound.headingMDBold)
-                        .foregroundStyle(.compound.textPrimary)
-                        .multilineTextAlignment(.center)
-                    Text(L10n.screenMediaBrowserDownloadErrorMessage)
-                        .font(.compound.bodyMD)
-                        .foregroundStyle(.compound.textPrimary)
-                        .multilineTextAlignment(.center)
-                }
-            }
-            .padding(.horizontal, 24)
-            .padding(.vertical, 40)
-            .background(.compound.bgSubtlePrimary, in: RoundedRectangle(cornerRadius: 14))
-        } else if shouldShowDownloadIndicator {
-            ProgressView()
-                .controlSize(.large)
-                .tint(.compound.iconPrimary)
-        }
-    }
-    
-    @ViewBuilder
-    private var caption: some View {
-        if case let .media(mediaItem) = currentItem, let caption = mediaItem.caption, !isFullScreen {
-            Text(caption)
-                .font(.compound.bodyLG)
-                .foregroundStyle(.compound.textPrimary)
-                .lineLimit(5)
-                .frame(maxWidth: .infinity, alignment: .leading)
-                .fixedSize(horizontal: false, vertical: true)
-                .padding(16)
-                .background {
-                    BlurEffectView(style: .systemChromeMaterial) // Darkest material available, matches the bottom bar when content is beneath.
-                        .ignoresSafeArea()
-                }
-                .transition(.move(edge: .bottom).combined(with: .opacity))
-        }
-    }
-    
-    @ToolbarContentBuilder
-    private var toolbar: some ToolbarContent {
-        ToolbarItem(placement: .cancellationAction) {
-            Button { context.send(viewAction: .dismiss) } label: {
-                Image(systemSymbol: .chevronBackward)
-                    .fontWeight(.semibold)
-            }
-            .tint(.compound.textActionPrimary) // These fix a bug where the light tint is shown when foregrounding the app.
-        }
-        
-        ToolbarItem(placement: .principal) {
-            toolbarHeader
-        }
-        
-        if case let .media(mediaItem) = currentItem {
-            ToolbarItem(placement: .primaryAction) {
-                Button { context.send(viewAction: .showItemDetails(mediaItem)) } label: {
-                    CompoundIcon(\.info)
-                }
-                .tint(.compound.textActionPrimary)
-            }
-        }
-    }
-    
-    @ViewBuilder
-    private var toolbarHeader: some View {
-        switch currentItem {
-        case .media(let mediaItem):
-            VStack(spacing: 0) {
-                Text(mediaItem.sender.displayName ?? mediaItem.sender.id)
-                    .font(.compound.bodySMSemibold)
-                    .foregroundStyle(.compound.textPrimary)
-                Text(mediaItem.timestamp.formatted(date: .abbreviated, time: .omitted))
-                    .font(.compound.bodyXS)
-                    .foregroundStyle(.compound.textPrimary)
-                    .textCase(.uppercase)
-            }
-        case .loading:
-            Text(L10n.commonLoadingMore)
-                .font(.compound.bodySMSemibold)
-                .foregroundStyle(.compound.textPrimary)
-        }
-    }
-}
-
-// MARK: - QuickLook
-
-private struct QuickLookView: UIViewControllerRepresentable {
-    let viewModelContext: TimelineMediaPreviewViewModel.Context
-
-    func makeUIViewController(context: Context) -> QLPreviewController {
-        context.coordinator.previewController
-    }
-
-    func updateUIViewController(_ uiViewController: QLPreviewController, context: Context) { }
-    
-    func makeCoordinator() -> Coordinator {
-        Coordinator(viewModelContext: viewModelContext)
-    }
-    
-    // MARK: Coordinator
-    
-    @MainActor class Coordinator {
-        let previewController = QLPreviewController()
-        
-        private let viewModelContext: TimelineMediaPreviewViewModel.Context
-        
-        private var cancellables: Set<AnyCancellable> = []
-        
-        init(viewModelContext: TimelineMediaPreviewViewModel.Context) {
-            self.viewModelContext = viewModelContext
-            
-            // Observation of currentPreviewItem doesn't work, so use the index instead.
-            previewController.publisher(for: \.currentPreviewItemIndex)
-                .sink { [weak self] _ in
-                    // This isn't removing duplicates which may try to download and/or write to disk concurrently????
-                    self?.loadCurrentItem()
-                }
-                .store(in: &cancellables)
-            
-            viewModelContext.viewState.dataSource.previewItemsPaginationPublisher
-                .sink { [weak self] in
-                    self?.handleUpdatedItems()
-                }
-                .store(in: &cancellables)
-            
-            viewModelContext.viewState.fileLoadedPublisher
-                .sink { [weak self] itemID in
-                    self?.handleFileLoaded(itemID: itemID)
-                }
-                .store(in: &cancellables)
-            
-            previewController.dataSource = viewModelContext.viewState.dataSource
-            previewController.currentPreviewItemIndex = viewModelContext.viewState.dataSource.initialItemIndex
-        }
-        
-        private func loadCurrentItem() {
-            if let previewItem = previewController.currentPreviewItem as? TimelineMediaPreviewItem.Media {
-                viewModelContext.send(viewAction: .updateCurrentItem(.media(previewItem)))
-            } else if let loadingItem = previewController.currentPreviewItem as? TimelineMediaPreviewItem.Loading {
-                switch loadingItem.state {
-                case .paginating:
-                    viewModelContext.send(viewAction: .updateCurrentItem(.loading(loadingItem)))
-                case .timelineStart:
-                    Task { await returnToIndex(viewModelContext.viewState.dataSource.firstPreviewItemIndex) }
-                case .timelineEnd:
-                    Task { await returnToIndex(viewModelContext.viewState.dataSource.lastPreviewItemIndex) }
-                }
-            } else {
-                MXLog.error("Unexpected preview item type: \(type(of: previewController.currentPreviewItem))")
-            }
-        }
-        
-        private func returnToIndex(_ index: Int) async {
-            // Sleep to fix a bug where the update didn't take effect when the swipe velocity was slow.
-            try? await Task.sleep(for: .seconds(0.1))
-            
-            previewController.currentPreviewItemIndex = index
-            viewModelContext.send(viewAction: .timelineEndReached)
-        }
-        
-        private func handleUpdatedItems() {
-            if previewController.currentPreviewItem is TimelineMediaPreviewItem.Loading {
-                let dataSource = viewModelContext.viewState.dataSource
-                if dataSource.previewController(previewController, previewItemAt: previewController.currentPreviewItemIndex) is TimelineMediaPreviewItem.Media {
-                    previewController.refreshCurrentPreviewItem() // This will trigger loadCurrentItem automatically.
-                }
-            }
-        }
-        
-        private func handleFileLoaded(itemID: TimelineItemIdentifier) {
-            guard (previewController.currentPreviewItem as? TimelineMediaPreviewItem.Media)?.id == itemID else { return }
-            previewController.refreshCurrentPreviewItem()
-        }
-    }
-}
-
-// MARK: - Previews
-
-struct TimelineMediaPreviewScreen_Previews: PreviewProvider {
-    @Namespace private static var namespace
-    
-    static let viewModel = makeViewModel()
-    static let downloadingViewModel = makeViewModel(isDownloading: true)
-    static let downloadErrorViewModel = makeViewModel(isDownloadError: true)
-    
-    static var previews: some View {
-        TimelineMediaPreviewScreen(context: viewModel.context)
-            .previewDisplayName("Normal")
-        TimelineMediaPreviewScreen(context: downloadingViewModel.context)
-            .previewDisplayName("Downloading")
-        TimelineMediaPreviewScreen(context: downloadErrorViewModel.context)
-            .previewDisplayName("Download Error")
-    }
-    
-    static func makeViewModel(isDownloading: Bool = false, isDownloadError: Bool = false) -> TimelineMediaPreviewViewModel {
-        let item = FileRoomTimelineItem(id: .randomEvent,
-                                        timestamp: .mock,
-                                        isOutgoing: false,
-                                        isEditable: false,
-                                        canBeRepliedTo: true,
-                                        isThreaded: false,
-                                        sender: .init(id: "", displayName: "Sally Sanderson"),
-                                        content: .init(filename: "Important document.pdf",
-                                                       caption: "A caption goes right here.",
-                                                       source: try? .init(url: .mockMXCFile, mimeType: nil),
-                                                       fileSize: 3 * 1024 * 1024,
-                                                       thumbnailSource: nil,
-                                                       contentType: .pdf))
-        
-        let timelineController = MockRoomTimelineController(timelineKind: .media(.mediaFilesScreen))
-        timelineController.timelineItems = [item]
-        
-        let mediaProvider = MediaProviderMock(configuration: .init())
-        
-        if isDownloading {
-            mediaProvider.loadFileFromSourceFilenameClosure = { _, _ in
-                try? await Task.sleep(for: .seconds(3600))
-                return .failure(.failedRetrievingFile)
-            }
-        } else if isDownloadError {
-            mediaProvider.loadFileFromSourceFilenameClosure = { _, _ in .failure(.failedRetrievingFile) }
-        }
-        
-        return TimelineMediaPreviewViewModel(context: .init(item: item,
-                                                            viewModel: TimelineViewModel.mock(timelineKind: timelineController.timelineKind,
-                                                                                              timelineController: timelineController),
-                                                            namespace: namespace),
-                                             mediaProvider: mediaProvider,
-                                             photoLibraryManager: PhotoLibraryManagerMock(.init()),
-                                             userIndicatorController: UserIndicatorControllerMock(),
-                                             appMediator: AppMediatorMock())
-    }
-}

ElementX/Sources/Screens/MediaEventsTimelineScreen/MediaEventsTimelineScreenCoordinator.swift

@@ -21,7 +21,7 @@ struct MediaEventsTimelineScreenCoordinatorParameters {
 }
 
 enum MediaEventsTimelineScreenCoordinatorAction {
-    case viewItem(TimelineMediaPreviewContext)
+    case viewInRoomTimeline(TimelineItemIdentifier)
 }
 
 final class MediaEventsTimelineScreenCoordinator: CoordinatorProtocol {
@@ -63,13 +63,14 @@ final class MediaEventsTimelineScreenCoordinator: CoordinatorProtocol {
         viewModel = MediaEventsTimelineScreenViewModel(mediaTimelineViewModel: mediaTimelineViewModel,
                                                        filesTimelineViewModel: filesTimelineViewModel,
                                                        mediaProvider: parameters.mediaProvider,
-                                                       userIndicatorController: parameters.userIndicatorController)
+                                                       userIndicatorController: parameters.userIndicatorController,
+                                                       appMediator: parameters.appMediator)
         
         viewModel.actionsPublisher
             .sink { [weak self] action in
                 switch action {
-                case .viewItem(let previewContext):
+                case .viewInRoomTimeline(let itemID):
-                    self?.actionsSubject.send(.viewItem(previewContext))
+                    self?.actionsSubject.send(.viewInRoomTimeline(itemID))
                 }
             }
             .store(in: &cancellables)

ElementX/Sources/Screens/MediaEventsTimelineScreen/MediaEventsTimelineScreenModels.swift

@@ -8,7 +8,7 @@
 import SwiftUI
 
 enum MediaEventsTimelineScreenViewModelAction {
-    case viewItem(TimelineMediaPreviewContext)
+    case viewInRoomTimeline(TimelineItemIdentifier)
 }
 
 enum MediaEventsTimelineScreenMode {
@@ -31,17 +31,16 @@ struct MediaEventsTimelineScreenViewState: BindableState {
     var activeTimelineContextProvider: (() -> TimelineViewModel.Context)!
     
     var bindings: MediaEventsTimelineScreenViewStateBindings
-    
-    var currentPreviewItemID: TimelineItemIdentifier?
 }
 
 struct MediaEventsTimelineScreenViewStateBindings {
     var screenMode: MediaEventsTimelineScreenMode
+    var mediaPreviewViewModel: TimelineMediaPreviewViewModel?
 }
 
 enum MediaEventsTimelineScreenViewAction {
     case changedScreenMode
     case oldestItemDidAppear
     case oldestItemDidDisappear
-    case tappedItem(item: RoomTimelineItemViewState, namespace: Namespace.ID)
+    case tappedItem(item: RoomTimelineItemViewState)
 }

ElementX/Sources/Screens/MediaEventsTimelineScreen/MediaEventsTimelineScreenViewModel.swift

@@ -13,7 +13,9 @@ typealias MediaEventsTimelineScreenViewModelType = StateStoreViewModel<MediaEven
 class MediaEventsTimelineScreenViewModel: MediaEventsTimelineScreenViewModelType, MediaEventsTimelineScreenViewModelProtocol {
     private let mediaTimelineViewModel: TimelineViewModelProtocol
     private let filesTimelineViewModel: TimelineViewModelProtocol
+    private let mediaProvider: MediaProviderProtocol
     private let userIndicatorController: UserIndicatorControllerProtocol
+    private let appMediator: AppMediatorProtocol
     
     private var isOldestItemVisible = false
     
@@ -37,10 +39,13 @@ class MediaEventsTimelineScreenViewModel: MediaEventsTimelineScreenViewModelType
          filesTimelineViewModel: TimelineViewModelProtocol,
          initialViewState: MediaEventsTimelineScreenViewState = .init(bindings: .init(screenMode: .media)),
          mediaProvider: MediaProviderProtocol,
-         userIndicatorController: UserIndicatorControllerProtocol) {
+         userIndicatorController: UserIndicatorControllerProtocol,
+         appMediator: AppMediatorProtocol) {
         self.mediaTimelineViewModel = mediaTimelineViewModel
         self.filesTimelineViewModel = filesTimelineViewModel
+        self.mediaProvider = mediaProvider
         self.userIndicatorController = userIndicatorController
+        self.appMediator = appMediator
         
         super.init(initialViewState: initialViewState, mediaProvider: mediaProvider)
         
@@ -84,8 +89,8 @@ class MediaEventsTimelineScreenViewModel: MediaEventsTimelineScreenViewModelType
             backPaginateIfNecessary(paginationStatus: activeTimelineViewModel.context.viewState.timelineState.paginationState.backward)
         case .oldestItemDidDisappear:
             isOldestItemVisible = false
-        case .tappedItem(let item, let namespace):
+        case .tappedItem(let item):
-            handleItemTapped(item, namespace: namespace)
+            handleItemTapped(item)
         }
     }
     
@@ -141,7 +146,7 @@ class MediaEventsTimelineScreenViewModel: MediaEventsTimelineScreenViewModelType
         }
     }
     
-    private func handleItemTapped(_ item: RoomTimelineItemViewState, namespace: Namespace.ID) {
+    private func handleItemTapped(_ item: RoomTimelineItemViewState) {
         let item: EventBasedMessageTimelineItemProtocol? = switch item.type {
         case .audio(let audioItem): audioItem
         case .file(let fileItem): fileItem
@@ -155,14 +160,25 @@ class MediaEventsTimelineScreenViewModel: MediaEventsTimelineScreenViewModelType
             return
         }
         
-        actionsSubject.send(.viewItem(.init(item: item,
+        let viewModel = TimelineMediaPreviewViewModel(initialItem: item,
-                                            viewModel: activeTimelineViewModel,
+                                                      timelineViewModel: activeTimelineViewModel,
-                                            namespace: namespace) { [weak self] itemID in
+                                                      mediaProvider: mediaProvider,
-                self?.state.currentPreviewItemID = itemID
+                                                      photoLibraryManager: PhotoLibraryManager(),
-            }))
+                                                      userIndicatorController: userIndicatorController,
+                                                      appMediator: appMediator)
+        viewModel.actions.sink { [weak self] action in
+            guard let self else { return }
+            switch action {
+            case .viewInRoomTimeline(let itemID):
+                state.bindings.mediaPreviewViewModel = nil
+                actionsSubject.send(.viewInRoomTimeline(itemID))
+            case .dismiss:
+                state.bindings.mediaPreviewViewModel = nil
+            }
+        }
+        .store(in: &cancellables)
         
-        // Set the current item in the next run loop so that (hopefully) the presentation will be ready before we flip the thumbnail.
+        state.bindings.mediaPreviewViewModel = viewModel
-        Task { state.currentPreviewItemID = item.id }
     }
     
     private func titleForDate(_ date: Date) -> String {

ElementX/Sources/Screens/MediaEventsTimelineScreen/View/MediaEventsTimelineScreen.swift

@@ -11,8 +11,6 @@ import SwiftUI
 struct MediaEventsTimelineScreen: View {
     @ObservedObject var context: MediaEventsTimelineScreenViewModel.Context
     
-    @Namespace private var zoomTransition
-    
     var body: some View {
         mainContent
             .navigationBarTitleDisplayMode(.inline)
@@ -25,6 +23,7 @@ struct MediaEventsTimelineScreen: View {
             .onChange(of: context.screenMode) { _, _ in
                 context.send(viewAction: .changedScreenMode)
             }
+            .timelineMediaPreview(viewModel: $context.mediaPreviewViewModel)
     }
     
     // The scale effects do the following:
@@ -65,9 +64,8 @@ struct MediaEventsTimelineScreen: View {
                             tappedItem(item)
                         } label: {
                             viewForTimelineItem(item)
-                                .scaleEffect(scale(for: item, isGridLayout: true))
+                                .scaleEffect(CGSize(width: -1, height: -1))
                         }
-                        .zoomTransitionSource(id: item.identifier, in: zoomTransition)
                     }
                 } footer: {
                     // Use a footer as the header because the scrollView is flipped
@@ -92,9 +90,8 @@ struct MediaEventsTimelineScreen: View {
                                 tappedItem(item)
                             } label: {
                                 viewForTimelineItem(item)
-                                    .scaleEffect(scale(for: item, isGridLayout: false))
+                                    .scaleEffect(CGSize(width: 1, height: -1))
                             }
-                            .zoomTransitionSource(id: item.identifier, in: zoomTransition)
                         }
                         .padding(.horizontal, 16)
                     }
@@ -216,16 +213,7 @@ struct MediaEventsTimelineScreen: View {
     }
     
     func tappedItem(_ item: RoomTimelineItemViewState) {
-        context.send(viewAction: .tappedItem(item: item, namespace: zoomTransition))
+        context.send(viewAction: .tappedItem(item: item))
-    }
-    
-    func scale(for item: RoomTimelineItemViewState, isGridLayout: Bool) -> CGSize {
-        if item.identifier == context.viewState.currentPreviewItemID, #available(iOS 18.0, *) {
-            // Remove the flip when presenting a preview so that the zoom transition is the right way up 🙃
-            CGSize(width: 1, height: 1)
-        } else {
-            CGSize(width: isGridLayout ? -1 : 1, height: -1)
-        }
     }
 }
 
@@ -265,7 +253,8 @@ struct MediaEventsTimelineScreen_Previews: PreviewProvider, TestablePreview {
                                            filesTimelineViewModel: makeTimelineViewModel(empty: empty),
                                            initialViewState: .init(bindings: .init(screenMode: screenMode)),
                                            mediaProvider: MediaProviderMock(configuration: .init()),
-                                           userIndicatorController: UserIndicatorControllerMock())
+                                           userIndicatorController: UserIndicatorControllerMock(),
+                                           appMediator: AppMediatorMock())
     }
     
     private static func makeTimelineViewModel(empty: Bool) -> TimelineViewModel {

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewDetailsView-iPad-en-GB.Loading.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:a30bdebdc1c816e6ca11cc4259749ec3e7f873e89c38e5cc64b23b5b7dcf7ebb
+oid sha256:7c08d326daa4e6f1daafeff7eafa3bc81b456bc6471e0e65d61bf01232583f84
-size 129684
+size 126883

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewDetailsView-iPad-pseudo.Loading.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:90f32840b85ff12b6de880e8ab1890f4442b873fac71083093324fc02e9700d3
+oid sha256:8a5e5762b6293e672af6521ee9608882ab58d0f855580685e52a33b288004f81
-size 128067
+size 126410

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewDetailsView-iPhone-16-en-GB.Loading.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:339faa15c493a6e36f0c567b89eb6d036010c5637a0be03f15f7915306612320
+oid sha256:4ae2436f59c028a6aa544b456d13135dc3b0b64cd14b1f964e8d8a03050ee2f6
-size 82212
+size 80579

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewDetailsView-iPhone-16-pseudo.Loading.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:04241b16f28aa03f42de4e365eadf80fca0637494e891eb5c81a337d7693f476
+oid sha256:01cd56cad5b5a73e4b6c3edccac2b2e31fd6ea13829ae3f551e3272b28c03192
-size 80107
+size 78920

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewRedactConfirmationView-iPad-en-GB.1.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:32ab5b9833a9213daf0a9688ac7d9db6fd112a312e725afe194d813951bb4268
+oid sha256:5c3a13b9e1975255bb09e0db46b67ea70fe6d88d5ce846a0d8e76b67cbee59f2
-size 119892
+size 118791

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewRedactConfirmationView-iPad-pseudo.1.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:a7b3fc983e75283a83041f37db96689af1487828d249a989d7ff10ec5c73f0f2
+oid sha256:953d61772a749a0aeca48c1ffaf5769ef9930b030c0804bfc7c39c9a279b5a0d
-size 128217
+size 127235

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewRedactConfirmationView-iPhone-16-en-GB.1.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:825917a093ef369a8b6583d825d675c9a44c96f2f6ab9cab2ec5c19e7508b425
+oid sha256:bf416680c94639c9f1f3002b210c8d8871ef2268acb2f8f89b8fb14c530b4969
-size 74696
+size 73718

PreviewTests/Sources/__Snapshots__/PreviewTests/test_timelineMediaPreviewRedactConfirmationView-iPhone-16-pseudo.1.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:ebc3ba85ab3bbd09db0a002fb3b729ebe1390d975061c6804c35d3da5822a1b7
+oid sha256:596cb5285a11299aa7cdbf2b55a44dfd45909d7c5ba95d90c34bc30929049a95
-size 87336
+size 86526

UnitTests/Sources/TimelineMediaPreviewViewModelTests.swift

@@ -51,7 +51,7 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         
         // When the preview controller sets an item that fails to load.
         mediaProvider.loadFileFromSourceFilenameClosure = { _, _ in .failure(.failedRetrievingFile) }
-        let failure = deferFailure(viewModel.state.fileLoadedPublisher, timeout: 1) { _ in true }
+        let failure = deferFailure(viewModel.state.previewControllerDriver, timeout: 1) { $0.isItemLoaded }
         context.send(viewAction: .updateCurrentItem(.media(context.viewState.dataSource.previewItems[0])))
         try await failure.fulfill()
         
@@ -66,7 +66,7 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         try await testLoadingItem()
         
         // When swiping to another item.
-        let deferred = deferFulfillment(viewModel.state.fileLoadedPublisher) { _ in true }
+        let deferred = deferFulfillment(viewModel.state.previewControllerDriver) { $0.isItemLoaded }
         context.send(viewAction: .updateCurrentItem(.media(context.viewState.dataSource.previewItems[1])))
         try await deferred.fulfill()
         
@@ -75,7 +75,7 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         XCTAssertEqual(context.viewState.currentItem, .media(context.viewState.dataSource.previewItems[1]))
         
         // When swiping back to the first item.
-        let failure = deferFailure(viewModel.state.fileLoadedPublisher, timeout: 1) { _ in true }
+        let failure = deferFailure(viewModel.state.previewControllerDriver, timeout: 1) { $0.isItemLoaded }
         context.send(viewAction: .updateCurrentItem(.media(context.viewState.dataSource.previewItems[0])))
         try await failure.fulfill()
         
@@ -89,9 +89,9 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         try await testLoadingItem()
         
         // When swiping to a "loading more" item.
-        let deferred = deferFailure(viewModel.state.fileLoadedPublisher, timeout: 1) { _ in true }
+        let failure = deferFailure(viewModel.state.previewControllerDriver, timeout: 1) { $0.isItemLoaded }
         context.send(viewAction: .updateCurrentItem(.loading(.paginating)))
-        try await deferred.fulfill()
+        try await failure.fulfill()
         
         // Then there should no longer be a media preview and no attempt should be made to load one.
         XCTAssertEqual(mediaProvider.loadFileFromSourceFilenameCallsCount, 1)
@@ -111,7 +111,7 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         
         // And the preview controller attempts to update the current item (now at a new index in the array but it hasn't changed in the data source).
         mediaProvider.loadFileFromSourceFilenameClosure = { _, _ in .failure(.failedRetrievingFile) }
-        let failure = deferFailure(viewModel.state.fileLoadedPublisher, timeout: 1) { _ in true }
+        let failure = deferFailure(viewModel.state.previewControllerDriver, timeout: 1) { $0.isItemLoaded }
         context.send(viewAction: .updateCurrentItem(.media(context.viewState.dataSource.previewItems[3])))
         try await failure.fulfill()
         
@@ -148,25 +148,27 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         }
         
         // When choosing to show the item details.
+        let deferredDriver = deferFulfillment(context.viewState.previewControllerDriver) { $0.isShowItemDetails }
         context.send(viewAction: .showItemDetails(mediaItem))
         
         // Then the details sheet should be presented.
-        guard let mediaDetailsItem = context.mediaDetailsItem else {
+        let action = try await deferredDriver.fulfill()
-            XCTFail("The default of the current item should be presented")
+        guard case let .showItemDetails(mediaDetailsItem) = action else {
+            XCTFail("The action should include the media item.")
             return
         }
         XCTAssertEqual(.media(mediaDetailsItem), context.viewState.currentItem)
         
         // When choosing to redact the item.
-        context.send(viewAction: .menuAction(.redact, item: mediaDetailsItem))
+        context.send(viewAction: .menuAction(.redact, item: mediaItem))
         
         // Then the confirmation sheet should be presented.
-        XCTAssertEqual(context.redactConfirmationItem, mediaDetailsItem)
+        XCTAssertEqual(context.redactConfirmationItem, mediaItem)
         XCTAssertFalse(timelineController.redactCalled)
         
         // When confirming the redaction.
         let deferred = deferFulfillment(viewModel.actions) { $0 == .dismiss }
-        context.send(viewAction: .redactConfirmation(item: mediaDetailsItem))
+        context.send(viewAction: .redactConfirmation(item: mediaItem))
         
         // Then the item should be redacted and the view should be dismissed.
         try await deferred.fulfill()
@@ -203,13 +205,12 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         XCTAssertEqual(mediaItem.contentType, "JPEG image")
         
         // When choosing to save the image.
-        let deferred = deferFulfillment(context.$viewState) { $0.bindings.alertInfo != nil }
+        let deferred = deferFulfillment(context.viewState.previewControllerDriver) { $0.isAuthorizationRequired }
         context.send(viewAction: .menuAction(.save, item: mediaItem))
-        try await deferred.fulfill()
         
         // Then the user should be prompted to allow access.
+        try await deferred.fulfill()
         XCTAssertTrue(photoLibraryManager.addResourceAtCalled)
-        XCTAssertEqual(context.alertInfo?.id, .authorizationRequired)
     }
     
     func testSaveVideo() async throws {
@@ -243,31 +244,24 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         XCTAssertEqual(mediaItem.contentType, "PDF document")
         
         // When choosing to save the file.
+        let deferred = deferFulfillment(context.viewState.previewControllerDriver) { $0.isExportFile }
         context.send(viewAction: .menuAction(.save, item: mediaItem))
-        try await Task.sleep(for: .seconds(0.5))
+        let exportAction = try await deferred.fulfill()
+        
+        guard case let .exportFile(file) = exportAction else {
+            XCTFail("Unexpected action")
+            return
+        }
         
         // Then the binding should be set for the user to export the file to their specified location.
         XCTAssertFalse(photoLibraryManager.addResourceAtCalled)
-        XCTAssertNotNil(context.fileToExport)
+        XCTAssertEqual(file.url, mediaItem.fileHandle?.url)
-        XCTAssertEqual(context.fileToExport?.url, mediaItem.fileHandle?.url)
-    }
-    
-    func testDismiss() async throws {
-        // Given a view model with a loaded item.
-        try await testLoadingItem()
-        
-        // When requesting to dismiss the view.
-        let deferred = deferFulfillment(viewModel.actions) { $0 == .dismiss }
-        context.send(viewAction: .dismiss)
-        
-        // Then the action should be sent upwards to make this happen.
-        try await deferred.fulfill()
     }
     
     // MARK: - Helpers
     
     private func loadInitialItem() async throws {
-        let deferred = deferFulfillment(viewModel.state.fileLoadedPublisher) { _ in true }
+        let deferred = deferFulfillment(viewModel.state.previewControllerDriver) { $0.isItemLoaded }
         let initialItem = context.viewState.dataSource.previewController(QLPreviewController(),
                                                                          previewItemAt: context.viewState.dataSource.initialItemIndex)
         guard let initialPreviewItem = initialItem as? TimelineMediaPreviewItem.Media else {
@@ -278,8 +272,6 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         try await deferred.fulfill()
     }
     
-    @Namespace private var testNamespace
-    
     private func setupViewModel(initialItemIndex: Int = 0, photoLibraryAuthorizationDenied: Bool = false) {
         let initialItems = makeItems()
         timelineController = MockRoomTimelineController(timelineKind: .media(.mediaFilesScreen))
@@ -288,10 +280,9 @@ class TimelineMediaPreviewViewModelTests: XCTestCase {
         mediaProvider = MediaProviderMock(configuration: .init())
         photoLibraryManager = PhotoLibraryManagerMock(.init(authorizationDenied: photoLibraryAuthorizationDenied))
         
-        viewModel = TimelineMediaPreviewViewModel(context: .init(item: initialItems[initialItemIndex],
+        viewModel = TimelineMediaPreviewViewModel(initialItem: initialItems[initialItemIndex],
-                                                                 viewModel: TimelineViewModel.mock(timelineKind: .media(.mediaFilesScreen),
+                                                  timelineViewModel: TimelineViewModel.mock(timelineKind: .media(.mediaFilesScreen),
-                                                                                                   timelineController: timelineController),
+                                                                                            timelineController: timelineController),
-                                                                 namespace: testNamespace),
                                                   mediaProvider: mediaProvider,
                                                   photoLibraryManager: photoLibraryManager,
                                                   userIndicatorController: UserIndicatorControllerMock(),