Fix vector-im/element-x-ios/issues/134 - Prevent home screen room last message attributed string from being computed on every update

Add async/await methods to the AttributedStringBuilder and adopt them throughout the app

ElementX/Sources/Services/Timeline/RoomTimelineController.swift

@@ -18,6 +18,11 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
     private let memberDetailProvider: MemberDetailProviderProtocol
     
     private var cancellables = Set<AnyCancellable>()
+    private var timelineItemsUpdateTask: Task<Void, Never>? {
+        willSet {
+            timelineItemsUpdateTask?.cancel()
+        }
+    }
     
     let callbacks = PassthroughSubject<RoomTimelineControllerCallback, Never>()
     
@@ -96,10 +101,20 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
     }
     
     private func updateTimelineItems() {
+        timelineItemsUpdateTask = Task {
+            await asyncUpdateTimelineItems()
+        }
+    }
+    
+    private func asyncUpdateTimelineItems() async {
         var newTimelineItems = [RoomTimelineItemProtocol]()
         
         var previousMessage: RoomMessageProtocol?
         for message in timelineProvider.messages {
+            if Task.isCancelled {
+                return
+            }
+            
             let areMessagesFromTheSameDay = haveSameDay(lhs: previousMessage, rhs: message)
             let shouldAddSectionHeader = !areMessagesFromTheSameDay
             
@@ -111,13 +126,17 @@ class RoomTimelineController: RoomTimelineControllerProtocol {
             let areMessagesFromTheSameSender = (previousMessage?.sender == message.sender)
             let shouldShowSenderDetails = !areMessagesFromTheSameSender || !areMessagesFromTheSameDay
             
-            newTimelineItems.append(timelineItemFactory.buildTimelineItemFor(message: message,
-                                                                             isOutgoing: message.sender == userId,
-                                                                             showSenderDetails: shouldShowSenderDetails))
+            newTimelineItems.append(await timelineItemFactory.buildTimelineItemFor(message: message,
+                                                                                   isOutgoing: message.sender == userId,
+                                                                                   showSenderDetails: shouldShowSenderDetails))
             
             previousMessage = message
         }
         
+        if Task.isCancelled {
+            return
+        }
+        
         timelineItems = newTimelineItems
         
         callbacks.send(.updatedTimelineItems)