Fixes #351 - Replace Syncing toast indicator with an in-timeline loading activity indicator (#378)

ElementX/Sources/Screens/RoomScreen/RoomScreenViewModel.swift

@@ -22,7 +22,6 @@ typealias RoomScreenViewModelType = StateStoreViewModel<RoomScreenViewState, Roo
 class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol {
     private enum Constants {
         static let backPaginationPageSize: UInt = 20
-        static let backPaginationIndicatorID = "RoomBackPagination"
     }
 
     private let timelineController: RoomTimelineControllerProtocol
@@ -31,10 +30,6 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
 
     // MARK: - Setup
         
-    deinit {
-        ServiceLocator.shared.userNotificationController.retractNotificationWithId(Constants.backPaginationIndicatorID)
-    }
-    
     init(timelineController: RoomTimelineControllerProtocol,
          timelineViewFactory: RoomTimelineViewFactoryProtocol,
          mediaProvider: MediaProviderProtocol,
@@ -66,13 +61,8 @@ class RoomScreenViewModel: RoomScreenViewModelType, RoomScreenViewModelProtocol
                     self.state.items[viewIndex] = timelineViewFactory.buildTimelineViewFor(timelineItem: timelineItem)
                 case .startedBackPaginating:
                     self.state.isBackPaginating = true
-                    ServiceLocator.shared.userNotificationController.submitNotification(UserNotification(id: Constants.backPaginationIndicatorID,
-                                                                                                         type: .toast,
-                                                                                                         title: ElementL10n.roomTimelineSyncing,
-                                                                                                         persistent: true))
                 case .finishedBackPaginating:
                     self.state.isBackPaginating = false
-                    ServiceLocator.shared.userNotificationController.retractNotificationWithId(Constants.backPaginationIndicatorID)
                 }
             }
             .store(in: &cancellables)

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

@@ -66,6 +66,7 @@ class TimelineTableViewController: UIViewController {
         didSet {
             // Paginate again if the threshold hasn't been satisfied.
             paginateBackwardsPublisher.send(())
+            applySnapshot()
         }
     }
     
@@ -197,6 +198,9 @@ class TimelineTableViewController: UIViewController {
             
             cell.item = timelineItem
             cell.contentConfiguration = UIHostingConfiguration {
+                if case .backPaginationIndicator = timelineItem {
+                    timelineItem
+                } else {
                     VStack {
                         if displayReactionsMenuForItemId == timelineItem.id {
                             TimelineItemReactionsMenuView { emoji in
@@ -230,6 +234,7 @@ class TimelineTableViewController: UIViewController {
                             }
                     }
                 }
+            }
             .margins(.all, self.timelineStyle.rowInsets)
             .minSize(height: 1)
             
@@ -248,6 +253,8 @@ class TimelineTableViewController: UIViewController {
         let previousLayout = layout()
         
         var snapshot = NSDiffableDataSourceSnapshot<TimelineSection, RoomTimelineViewProvider>()
+        snapshot.appendSections([.loadingIndicator])
+        snapshot.appendItems([.backPaginationIndicator(isBackPaginating)])
         snapshot.appendSections([.main])
         snapshot.appendItems(timelineItems)
         dataSource.apply(snapshot, animatingDifferences: false)
@@ -409,7 +416,10 @@ extension TimelineTableViewController: UITableViewDelegate {
 
 extension TimelineTableViewController {
     /// The sections of the table view used in the diffable data source.
-    enum TimelineSection { case main }
+    enum TimelineSection {
+        case loadingIndicator
+        case main
+    }
     
     /// A description of the timeline's layout.
     struct LayoutDescriptor {

ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineViewProvider.swift

@@ -27,6 +27,7 @@ enum RoomTimelineViewProvider: Identifiable, Hashable {
     case notice(NoticeRoomTimelineItem)
     case redacted(RedactedRoomTimelineItem)
     case encrypted(EncryptedRoomTimelineItem)
+    case backPaginationIndicator(Bool)
     
     var id: String {
         switch self {
@@ -48,6 +49,8 @@ enum RoomTimelineViewProvider: Identifiable, Hashable {
             return item.id
         case .encrypted(let item):
             return item.id
+        case .backPaginationIndicator:
+            return "BackpaginationLoadingIndicator"
         }
     }
 }
@@ -73,6 +76,10 @@ extension RoomTimelineViewProvider: View {
             RedactedRoomTimelineView(timelineItem: item)
         case .encrypted(let item):
             EncryptedRoomTimelineView(timelineItem: item)
+        case .backPaginationIndicator(let isBackPaginating):
+            ProgressView()
+                .frame(maxWidth: .infinity)
+                .opacity(isBackPaginating ? 1.0 : 0.0)
         }
     }
 }