Better timeline handling, based on improved rust APIs.

ElementX.xcodeproj/project.pbxproj

@@ -8,16 +8,19 @@
 
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+		184B31DF27D898960075A669 /* Introspect in Frameworks */ = {isa = PBXBuildFile; productRef = 184B31DE27D898960075A669 /* Introspect */; };
 		1850253F27B6918D002E6B18 /* ElementXTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1850253E27B6918D002E6B18 /* ElementXTests.swift */; };
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-		1850255927B69388002E6B18 /* MatrixRustSDK in Frameworks */ = {isa = PBXBuildFile; productRef = 1850255827B69388002E6B18 /* MatrixRustSDK */; };
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 		1850256F27B6A135002E6B18 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 1850256527B6A135002E6B18 /* AppDelegate.swift */; };
 		1850257027B6A135002E6B18 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 1850256827B6A135002E6B18 /* Assets.xcassets */; };
 		1850257127B6A135002E6B18 /* LaunchScreen.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 1850256927B6A135002E6B18 /* LaunchScreen.storyboard */; };
+		1859CF5527D7A6FF00E86E4E /* MatrixRustSDK in Frameworks */ = {isa = PBXBuildFile; productRef = 1859CF5427D7A6FF00E86E4E /* MatrixRustSDK */; };
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+		18A318DC27DA42C9000867CD /* RoomTimelineItemProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18A318DA27DA42C9000867CD /* RoomTimelineItemProtocol.swift */; };
+		18A318DD27DA42C9000867CD /* TextRoomTimelineItem.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18A318DB27DA42C9000867CD /* TextRoomTimelineItem.swift */; };
 		18F2BAD727D25B4000DD1988 /* RoomProxyProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BA7327D25B4000DD1988 /* RoomProxyProtocol.swift */; };
 		18F2BAD827D25B4000DD1988 /* RoomProxy.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BA7427D25B4000DD1988 /* RoomProxy.swift */; };
 		18F2BAD927D25B4000DD1988 /* MockRoomProxy.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BA7527D25B4000DD1988 /* MockRoomProxy.swift */; };
@@ -76,8 +79,6 @@
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 		18F2BB2127D25D3C00DD1988 /* HomeScreenUITests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BAA727D25B4000DD1988 /* HomeScreenUITests.swift */; };
 		18F2BB2227D25D4600DD1988 /* LoginScreenUITests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BACF27D25B4000DD1988 /* LoginScreenUITests.swift */; };
-		18F2BB2427D262A900DD1988 /* RoomTimelineItemProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BB2327D262A900DD1988 /* RoomTimelineItemProtocol.swift */; };
-		18F2BB2627D262FA00DD1988 /* TextRoomTimelineItem.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BB2527D262FA00DD1988 /* TextRoomTimelineItem.swift */; };
 		18F2BB2827D2647A00DD1988 /* MockRoomTimelineController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BB2727D2647A00DD1988 /* MockRoomTimelineController.swift */; };
 		18F2BB2A27D2648900DD1988 /* RoomTimelineControllerProtocol.swift in Sources */ = {isa = PBXBuildFile; fileRef = 18F2BB2927D2648900DD1988 /* RoomTimelineControllerProtocol.swift */; };
 /* End PBXBuildFile section */
@@ -111,6 +112,9 @@
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 		1850256A27B6A135002E6B18 /* Base */ = {isa = PBXFileReference; lastKnownFileType = file.storyboard; name = Base; path = Base.lproj/LaunchScreen.storyboard; sourceTree = "<group>"; };
+		18A318D827D9E7AD000867CD /* matrix-rust-components-swift */ = {isa = PBXFileReference; lastKnownFileType = wrapper; name = "matrix-rust-components-swift"; path = "../matrix-rust-components-swift"; sourceTree = "<group>"; };
+		18A318DA27DA42C9000867CD /* RoomTimelineItemProtocol.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RoomTimelineItemProtocol.swift; sourceTree = "<group>"; };
+		18A318DB27DA42C9000867CD /* TextRoomTimelineItem.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = TextRoomTimelineItem.swift; sourceTree = "<group>"; };
 		18F2BA7327D25B4000DD1988 /* RoomProxyProtocol.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RoomProxyProtocol.swift; sourceTree = "<group>"; };
 		18F2BA7427D25B4000DD1988 /* RoomProxy.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RoomProxy.swift; sourceTree = "<group>"; };
 		18F2BA7527D25B4000DD1988 /* MockRoomProxy.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = MockRoomProxy.swift; sourceTree = "<group>"; };
@@ -169,8 +173,6 @@
 		18F2BAD427D25B4000DD1988 /* LoginScreenCoordinator.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LoginScreenCoordinator.swift; sourceTree = "<group>"; };
 		18F2BAD627D25B4000DD1988 /* LoginScreen.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = LoginScreen.swift; sourceTree = "<group>"; };
 		18F2BB1927D25BE800DD1988 /* RoomTimelineController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomTimelineController.swift; sourceTree = "<group>"; };
-		18F2BB2327D262A900DD1988 /* RoomTimelineItemProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomTimelineItemProtocol.swift; sourceTree = "<group>"; };
-		18F2BB2527D262FA00DD1988 /* TextRoomTimelineItem.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TextRoomTimelineItem.swift; sourceTree = "<group>"; };
 		18F2BB2727D2647A00DD1988 /* MockRoomTimelineController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MockRoomTimelineController.swift; sourceTree = "<group>"; };
 		18F2BB2927D2648900DD1988 /* RoomTimelineControllerProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomTimelineControllerProtocol.swift; sourceTree = "<group>"; };
 		18FE279627C7B85300016375 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
@@ -183,7 +185,8 @@
 			files = (
 				182BC48127C4EBBB00A30C33 /* Kingfisher in Frameworks */,
 				1863A3FC27BA5A9100B52E4D /* KeychainAccess in Frameworks */,
-				1850255927B69388002E6B18 /* MatrixRustSDK in Frameworks */,
+				184B31DF27D898960075A669 /* Introspect in Frameworks */,
+				1859CF5527D7A6FF00E86E4E /* MatrixRustSDK in Frameworks */,
 				1863A40627BA6DFC00B52E4D /* SwiftyBeaver in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -208,6 +211,7 @@
 		1850251B27B6918C002E6B18 = {
 			isa = PBXGroup;
 			children = (
+				18A318D827D9E7AD000867CD /* matrix-rust-components-swift */,
 				1850252627B6918C002E6B18 /* ElementX */,
 				1850253D27B6918D002E6B18 /* ElementXTests */,
 				1850254727B6918D002E6B18 /* ElementXUITests */,
@@ -274,6 +278,15 @@
 			path = "Supporting Files";
 			sourceTree = "<group>";
 		};
+		18A318D927DA42C9000867CD /* TimelineItems */ = {
+			isa = PBXGroup;
+			children = (
+				18A318DA27DA42C9000867CD /* RoomTimelineItemProtocol.swift */,
+				18A318DB27DA42C9000867CD /* TextRoomTimelineItem.swift */,
+			);
+			path = TimelineItems;
+			sourceTree = "<group>";
+		};
 		18F2BA7227D25B4000DD1988 /* Services */ = {
 			isa = PBXGroup;
 			children = (
@@ -293,8 +306,7 @@
 				18F2BB1927D25BE800DD1988 /* RoomTimelineController.swift */,
 				18F2BB2727D2647A00DD1988 /* MockRoomTimelineController.swift */,
 				18F2BA7727D25B4000DD1988 /* RoomTimelineProvider.swift */,
-				18F2BB2327D262A900DD1988 /* RoomTimelineItemProtocol.swift */,
+				18A318D927DA42C9000867CD /* TimelineItems */,
-				18F2BB2527D262FA00DD1988 /* TextRoomTimelineItem.swift */,
 			);
 			path = Timeline;
 			sourceTree = "<group>";
@@ -575,10 +587,11 @@
 			);
 			name = ElementX;
 			packageProductDependencies = (
-				1850255827B69388002E6B18 /* MatrixRustSDK */,
 				1863A3FB27BA5A9100B52E4D /* KeychainAccess */,
 				1863A40527BA6DFC00B52E4D /* SwiftyBeaver */,
 				182BC48027C4EBBB00A30C33 /* Kingfisher */,
+				1859CF5427D7A6FF00E86E4E /* MatrixRustSDK */,
+				184B31DE27D898960075A669 /* Introspect */,
 			);
 			productName = ElementX;
 			productReference = 1850252427B6918C002E6B18 /* ElementX.app */;
@@ -654,10 +667,11 @@
 			);
 			mainGroup = 1850251B27B6918C002E6B18;
 			packageReferences = (
-				1850255727B69388002E6B18 /* XCRemoteSwiftPackageReference "matrix-rust-components-swift" */,
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 				1863A40427BA6DFC00B52E4D /* XCRemoteSwiftPackageReference "SwiftyBeaver" */,
 				182BC47F27C4EBBB00A30C33 /* XCRemoteSwiftPackageReference "Kingfisher" */,
+				1859CF5327D7A6FF00E86E4E /* XCRemoteSwiftPackageReference "matrix-rust-components-swift" */,
+				184B31DD27D898960075A669 /* XCRemoteSwiftPackageReference "SwiftUI-Introspect" */,
 			);
 			productRefGroup = 1850252527B6918C002E6B18 /* Products */;
 			projectDirPath = "";
@@ -728,6 +742,7 @@
 				18F2BAFF27D25B4000DD1988 /* HomeScreenModels.swift in Sources */,
 				18F2BB1527D25B4000DD1988 /* LoginScreenViewModelProtocol.swift in Sources */,
 				18F2BAEB27D25B4000DD1988 /* LabelledActivityIndicatorView.swift in Sources */,
+				18A318DC27DA42C9000867CD /* RoomTimelineItemProtocol.swift in Sources */,
 				18F2BAE427D25B4000DD1988 /* Presentable.swift in Sources */,
 				18F2BAF927D25B4000DD1988 /* SplashViewController.swift in Sources */,
 				18F2BAE327D25B4000DD1988 /* RootRouter.swift in Sources */,
@@ -736,7 +751,6 @@
 				18F2BAD927D25B4000DD1988 /* MockRoomProxy.swift in Sources */,
 				18F2BAE727D25B4000DD1988 /* RoundedToastView.swift in Sources */,
 				18F2BAF227D25B4000DD1988 /* WeakDictionaryKeyReference.swift in Sources */,
-				18F2BB2427D262A900DD1988 /* RoomTimelineItemProtocol.swift in Sources */,
 				18F2BAE027D25B4000DD1988 /* NavigationRouter.swift in Sources */,
 				18F2BAF627D25B4000DD1988 /* Coordinator.swift in Sources */,
 				18F2BAEA27D25B4000DD1988 /* ActivityCenter.swift in Sources */,
@@ -761,7 +775,6 @@
 				18F2BADF27D25B4000DD1988 /* NavigationRouterStore.swift in Sources */,
 				18F2BAFE27D25B4000DD1988 /* HomeScreenViewModelProtocol.swift in Sources */,
 				18F2BAE827D25B4000DD1988 /* RectangleToastView.swift in Sources */,
-				18F2BB2627D262FA00DD1988 /* TextRoomTimelineItem.swift in Sources */,
 				18F2BB1627D25B4000DD1988 /* LoginScreenModels.swift in Sources */,
 				18F2BADA27D25B4000DD1988 /* RoomTimelineProvider.swift in Sources */,
 				18F2BB0027D25B4000DD1988 /* HomeScreen.swift in Sources */,
@@ -769,6 +782,7 @@
 				18F2BB0127D25B4000DD1988 /* HomeScreenViewModel.swift in Sources */,
 				18F2BAF027D25B4000DD1988 /* ActivityDismissal.swift in Sources */,
 				18F2BADD27D25B4000DD1988 /* KeychainController.swift in Sources */,
+				18A318DD27DA42C9000867CD /* TextRoomTimelineItem.swift in Sources */,
 				18F2BAFB27D25B4000DD1988 /* HomeScreenCoordinator.swift in Sources */,
 				18F2BB0C27D25B4000DD1988 /* RoomScreenCoordinator.swift in Sources */,
 				18F2BB0E27D25B4000DD1988 /* RoomScreenViewModelProtocol.swift in Sources */,
@@ -1136,7 +1150,15 @@
 				minimumVersion = 7.0.0;
 			};
 		};
-		1850255727B69388002E6B18 /* XCRemoteSwiftPackageReference "matrix-rust-components-swift" */ = {
+		184B31DD27D898960075A669 /* XCRemoteSwiftPackageReference "SwiftUI-Introspect" */ = {
+			isa = XCRemoteSwiftPackageReference;
+			repositoryURL = "https://github.com/siteline/SwiftUI-Introspect.git";
+			requirement = {
+				branch = master;
+				kind = branch;
+			};
+		};
+		1859CF5327D7A6FF00E86E4E /* XCRemoteSwiftPackageReference "matrix-rust-components-swift" */ = {
 			isa = XCRemoteSwiftPackageReference;
 			repositoryURL = "https://github.com/matrix-org/matrix-rust-components-swift.git";
 			requirement = {
@@ -1168,9 +1190,14 @@
 			package = 182BC47F27C4EBBB00A30C33 /* XCRemoteSwiftPackageReference "Kingfisher" */;
 			productName = Kingfisher;
 		};
-		1850255827B69388002E6B18 /* MatrixRustSDK */ = {
+		184B31DE27D898960075A669 /* Introspect */ = {
 			isa = XCSwiftPackageProductDependency;
-			package = 1850255727B69388002E6B18 /* XCRemoteSwiftPackageReference "matrix-rust-components-swift" */;
+			package = 184B31DD27D898960075A669 /* XCRemoteSwiftPackageReference "SwiftUI-Introspect" */;
+			productName = Introspect;
+		};
+		1859CF5427D7A6FF00E86E4E /* MatrixRustSDK */ = {
+			isa = XCSwiftPackageProductDependency;
+			package = 1859CF5327D7A6FF00E86E4E /* XCRemoteSwiftPackageReference "matrix-rust-components-swift" */;
 			productName = MatrixRustSDK;
 		};
 		1863A3FB27BA5A9100B52E4D /* KeychainAccess */ = {

ElementX/Sources/Screens/HomeScreen/HomeScreenViewModel.swift

@@ -66,8 +66,7 @@ class HomeScreenViewModel: HomeScreenViewModelType, HomeScreenViewModelProtocol
         self.roomList = roomList
         
         roomList.forEach({ roomProxy  in
-            roomProxy.paginateBackwards(start: 0, finish: 1)
+            roomProxy.paginateBackwards(count: 1, callback: nil)
-            roomProxy.startLiveEventListener()
             roomProxy.callbacks.sink { [weak self] callback in
                 switch callback {
                 case .updatedLastMessage:

ElementX/Sources/Screens/RoomScreen/RoomScreenModels.swift

@@ -32,7 +32,6 @@ private var dateFormatter: DateFormatter = {
 }()
 
 struct RoomScreenMessage: Identifiable, Equatable {
-    
     let id: String
     let sender: String
     let text: String
@@ -45,6 +44,5 @@ struct RoomScreenMessage: Identifiable, Equatable {
 
 struct RoomScreenViewState: BindableState {
     var roomTitle: String?
-    var isLoading: Bool = false
     var messages: [RoomScreenMessage] = []
 }

ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift

@@ -50,8 +50,6 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
                 self.state.messages = self.buildRoomScreenMessages(timelineController.timelineItems)
             }
         }.store(in: &cancellables)
-        
-        timelineController.paginateBackwards(Constants.backPaginationPageSize)
     }
 
     // MARK: - Public

ElementX/Sources/Screens/RoomScreen/View/RoomScreen.swift

@@ -15,33 +15,47 @@
 //
 
 import SwiftUI
+import Introspect
+import Combine
 
 struct RoomScreen: View {
     
-    let timelineBottomDividerIdentifier = "TimelineBottomDividerIdentifier"
+    @State private var scrollViewObserver: ScrollViewObserver = ScrollViewObserver()
+    @State private var messages: [RoomScreenMessage] = []
+    
+    @State private var didRequestBackPagination = false
+    @State private var hasPendingMessages = false
+    @State private var wasBottomVisible = false
+    
+    @State private var previousTopMostMessageIdentifier: String?
+    
+    private let timelineBottomAnchor = "TimelineBottomAnchor"
     
     @ObservedObject var context: RoomScreenViewModel.Context
-    @State var backPaginationMessageIdentifier: String?
     
     var body: some View {
-        ScrollViewReader { reader in
+        ScrollViewReader { scrollViewProxy in
             List {
-                if backPaginationMessageIdentifier != nil {
+                if didRequestBackPagination == false {
+                    Color
+                        .clear
+                        .onAppear {
+                            guard didRequestBackPagination == false else {
+                                return
+                            }
+
+                            didRequestBackPagination = true
+                            context.send(viewAction: .loadPreviousPage)
+                        }
+                } else {
                     HStack {
                         Spacer()
                         ProgressView()
                         Spacer()
                     }
-                } else {
-                    Rectangle()
-                        .onAppear {
-                            let _ = MXLog.debug("Request load previous page")
-                            backPaginationMessageIdentifier = context.viewState.messages.first?.id
-                            context.send(viewAction: .loadPreviousPage)
-                        }
-                        .frame(height: 0.0)
                 }
-                ForEach(context.viewState.messages) { message in
+                
+                ForEach(messages) { message in
                     VStack(alignment: .leading) {
                         HStack {
                             Text(message.sender)
@@ -55,23 +69,117 @@ struct RoomScreen: View {
                     .id(message.id)
                 }
                 
-                Divider()
+                Color.clear
-                    .id(timelineBottomDividerIdentifier)
                     .listRowSeparator(.hidden)
+                    .id(timelineBottomAnchor)
             }
             .listStyle(.plain)
-            .onAppear {
+            .environment(\.defaultMinListRowHeight, 0.0)
-                reader.scrollTo(timelineBottomDividerIdentifier, anchor: .bottom)
+            .navigationBarTitleDisplayMode(.inline)
-            }
+            // Fetch the underlying UIScrollView and start observing it
-            .onChange(of: context.viewState.messages) { _ in
+            .introspectTableView { scrollView in
-                if backPaginationMessageIdentifier != nil {
+                if scrollView == scrollViewObserver.scrollView {
-                    reader.scrollTo(backPaginationMessageIdentifier, anchor: .bottom)
-                    self.backPaginationMessageIdentifier = nil
                     return
                 }
                 
-                reader.scrollTo(timelineBottomDividerIdentifier, anchor: .bottom)
+                scrollViewObserver = ScrollViewObserver(scrollView: scrollView)
             }
+            // Scroll to the bottom when the timeline first appears
+            .onAppear {
+                scrollViewProxy.scrollTo(timelineBottomAnchor, anchor: .bottom)
+            }
+            // When the view state changes check whether the user is interacting with the scroll view.
+            // Updating in that case causes undesired scrolling. Delay until the scroll view stops scrolling.
+            // Also store previous top most message identifier to have something to scroll to after the update.
+            .onChange(of: context.viewState.messages) { newValue in
+                previousTopMostMessageIdentifier = messages.first?.id
+                wasBottomVisible = scrollViewObserver.isBottomVisible
+                
+                if scrollViewObserver.isTracking == true {
+                    hasPendingMessages = true
+                    return
+                }
+                
+                messages = newValue
+            }
+            // Check if we have pending messages to apply and apply them when the scroll finishes scrolling
+            .onReceive(scrollViewObserver.didEndScrolling, perform: {
+                if hasPendingMessages {
+                    messages = context.viewState.messages
+                    hasPendingMessages = false
+                }
+            })
+            // Process timeline updates
+            .onChange(of: messages, perform: { _ in
+                if didRequestBackPagination && wasBottomVisible {
+                    scrollViewProxy.scrollTo(timelineBottomAnchor, anchor: .bottom)
+                } else if didRequestBackPagination == false {
+                    if wasBottomVisible {
+                        scrollViewProxy.scrollTo(timelineBottomAnchor, anchor: .bottom)
+                    }
+                } else {
+                    // Manual scrolling breaks inertia. Don't do it if the scroll view is decelerating
+                    if scrollViewObserver.isDecelerating == false {
+                        scrollViewProxy.scrollTo(previousTopMostMessageIdentifier, anchor: .top)
+                    }
+                }
+                
+                didRequestBackPagination = false
+            })
+        }
+    }
+}
+
+/// Simple wrapper around an UIScrollView that publishes when it finishes scrolling
+class ScrollViewObserver: NSObject, UIScrollViewDelegate {
+    private(set) var scrollView: UIScrollView?
+    
+    let didEndScrolling = PassthroughSubject<Void, Never>()
+    
+    override init() {
+        
+    }
+    
+    init(scrollView: UIScrollView) {
+        self.scrollView = scrollView
+        super.init()
+        
+        scrollView.delegate = self
+    }
+    
+    var isTracking: Bool {
+        self.scrollView?.isTracking == true
+    }
+    
+    var isDecelerating: Bool {
+        self.scrollView?.isDecelerating == true
+    }
+    
+    var isTopVisible: Bool {
+        guard let scrollView = scrollView else {
+            return false
+        }
+
+        return (scrollView.contentOffset.y + scrollView.adjustedContentInset.top) <= 0.0
+    }
+    
+    var isBottomVisible: Bool {
+        guard let scrollView = scrollView else {
+            return false
+        }
+
+        return (scrollView.contentOffset.y) >= (scrollView.contentSize.height - scrollView.frame.size.height)
+    }
+    
+    // MARK: - UIScrollViewDelegate
+    
+    func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
+        didEndScrolling.send(())
+    }
+    
+    func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerating: Bool) {
+        if decelerating == false {
+            didEndScrolling.send(())
         }
     }
 }

ElementX/Sources/Services/MockRoomProxy.swift

@@ -8,6 +8,7 @@
 import Foundation
 import UIKit
 import Combine
+import MatrixRustSDK
 
 struct MockRoomProxy: RoomProxyProtocol {
     let id = UUID().uuidString
@@ -38,7 +39,7 @@ struct MockRoomProxy: RoomProxyProtocol {
         
     }
     
-    func paginateBackwards(start: UInt, finish: UInt) {
+    func paginateBackwards(count: UInt, callback: ((Result<[Message], Error>) -> Void)?) {
         
     }
 }

ElementX/Sources/Services/RoomProxy.swift

@@ -14,6 +14,7 @@ import MatrixRustSDK
 enum RoomProxyError: Error {
     case failedRetrievingDisplayName
     case failedRetrievingAvatar
+    case backwardStreamNotAvailable
 }
 
 private class WeakRoomProxyWrapper: RoomDelegate {
@@ -23,27 +24,32 @@ private class WeakRoomProxyWrapper: RoomDelegate {
         self.roomProxy = roomProxy
     }
     
+    // MARK: - RoomDelegate
+    
     func didReceiveMessage(message: Message) {
         DispatchQueue.main.async {
             self.roomProxy?.appendMessage(message)
         }
     }
-    
-    func didPaginateBackwards(messages: [Message]) {
-        DispatchQueue.main.async {
-            self.roomProxy?.preprendMessages(messages)
-        }
-    }
 }
 
 class RoomProxy: RoomProxyProtocol, Equatable {
     private let room: Room
+    private let processingQueue: DispatchQueue
+    
+    private var backwardStream: BackwardsStreamProtocol?
     
     let callbacks = PassthroughSubject<RoomProxyCallback, Never>()
     
     init(room: Room) {
         self.room = room
-        self.room.setDelegate(delegate: WeakRoomProxyWrapper(roomProxy: self))
+        processingQueue = DispatchQueue(label: "RoomProxyProcessingQueue")
+        
+        processingQueue.async {
+            self.backwardStream = room.startLiveEventListener()
+        }
+        
+        room.setDelegate(delegate: WeakRoomProxyWrapper(roomProxy: self))
     }
     
     var id: String {
@@ -119,13 +125,26 @@ class RoomProxy: RoomProxyProtocol, Equatable {
             }
         }
     }
-    
+        
-    func startLiveEventListener() {
+    func paginateBackwards(count: UInt, callback: ((Result<[Message], Error>) -> Void)?) {
-        room.startLiveEventListener()
+        processingQueue.async {
-    }
+            guard let backwardStream = self.backwardStream else {
-    
+                DispatchQueue.main.async {
-    func paginateBackwards(start: UInt, finish: UInt) {
+                    callback?(.failure(RoomProxyError.backwardStreamNotAvailable))
-        room.paginateBackwards(from: UInt8(start), to: UInt8(finish))
+                }
+                return
+            }
+            
+            let messages = backwardStream.paginateBackwards(count: UInt64(count))
+            
+            DispatchQueue.main.async {                
+                callback?(.success(messages))
+                
+                if self.lastMessage == nil {
+                    self.lastMessage = messages.last?.content()
+                }
+            }
+        }
     }
     
     // MARK: - Equatable
@@ -137,11 +156,7 @@ class RoomProxy: RoomProxyProtocol, Equatable {
     // MARK: - Private
     
     fileprivate func preprendMessages(_ messages: [Message]) {
-        if lastMessage == nil {
-            lastMessage = messages.last?.content()
-        }
         
-        callbacks.send(.prependedMessages(messages))
     }
     
     fileprivate func appendMessage(_ message: Message) {

ElementX/Sources/Services/RoomProxyProtocol.swift

@@ -10,7 +10,6 @@ import Combine
 import MatrixRustSDK
 
 enum RoomProxyCallback {
-    case prependedMessages([Message])
     case addedMessage(Message)
     case updatedLastMessage
 }
@@ -32,8 +31,7 @@ protocol RoomProxyProtocol {
     func loadDisplayName(_ completion: @escaping (Result<String, Error>) -> Void)
     func loadAvatar(_ completion: @escaping (Result<UIImage?, Error>) -> Void)
     
-    func startLiveEventListener()
+    func paginateBackwards(count: UInt, callback: ((Result<[Message], Error>) -> Void)?)
-    func paginateBackwards(start: UInt, finish: UInt)
     
     var callbacks: PassthroughSubject<RoomProxyCallback, Never> { get }
 }

ElementX/Sources/Services/Timeline/RoomTimelineProvider.swift

@@ -19,7 +19,6 @@ class RoomTimelineProvider {
     private var cancellables = Set<AnyCancellable>()
     
     private var paginationCounter: UInt = 0
-    private var isWaitingPaginationResponse = false
     
     let callbacks = PassthroughSubject<RoomTimelineCallback, Never>()
     private(set) var messages = [Message]()
@@ -27,17 +26,12 @@ class RoomTimelineProvider {
     init(roomProxy: RoomProxyProtocol) {
         self.roomProxy = roomProxy
         
-        self.roomProxy.startLiveEventListener()
-        
         self.roomProxy.callbacks.sink { [weak self] callback in
             guard let self = self else { return }
             
             switch callback {
             case .addedMessage(let message):
                 self.messages.append(message)
-            case .prependedMessages(let messages):
-                self.messages.insert(contentsOf: messages.reversed(), at: 0)
-                self.isWaitingPaginationResponse = false
             case .updatedLastMessage:
                 break
             }
@@ -48,14 +42,15 @@ class RoomTimelineProvider {
     }
     
     func paginateBackwards(_ count: UInt) {
-        if isWaitingPaginationResponse {
+        self.roomProxy.paginateBackwards(count: count) { result in
-            return
+            switch result {
+            case .success(let messages):
+                self.messages.insert(contentsOf: messages.reversed(), at: 0)
+                self.callbacks.send(.updatedMessages)
+            case .failure(let error):
+                MXLog.debug("Failed paginating backwards with error: \(error)")
+                self.callbacks.send(.updatedMessages)
+            }
         }
-        
-        self.roomProxy.paginateBackwards(start: paginationCounter, finish: count)
-        isWaitingPaginationResponse = true
-        
-        // This is not in any way correct but it will do for now.
-        self.paginationCounter += count
     }
 }