Implemented updating channels before screen display

Author: martinmitrevski

Sources/StreamChatSwiftUI/ChatChannelList/ChatChannelListItem.swift

@@ -16,6 +16,7 @@ public struct ChatChannelListItem: View {
 
     var channel: ChatChannel
     var channelName: String
+    var injectedChannelInfo: InjectedChannelInfo?
     var avatar: UIImage
     var onlineIndicatorShown: Bool
     var disabled = false
@@ -37,7 +38,7 @@ public struct ChatChannelListItem: View {
 
                         Spacer()
 
-                        if channel.unreadCount != .noUnread {
+                        if injectedChannelInfo == nil && channel.unreadCount != .noUnread {
                             UnreadIndicatorView(
                                 unreadCount: channel.unreadCount.messages
                             )
@@ -59,7 +60,7 @@ public struct ChatChannelListItem: View {
                                     showReadCount: false
                                 )
                             }
-                            SubtitleText(text: timestampText)
+                            SubtitleText(text: injectedChannelInfo?.timestamp ?? channel.timestampText)
                         }
                     }
                 }
@@ -79,27 +80,15 @@ public struct ChatChannelListItem: View {
                     .frame(maxHeight: 12)
                     .foregroundColor(Color(colors.subtitleText))
             } else {
-                if shouldShowTypingIndicator {
+                if channel.shouldShowTypingIndicator {
                     TypingIndicatorView()
                 }
             }
-            SubtitleText(text: subtitleText)
+            SubtitleText(text: injectedChannelInfo?.subtitle ?? channel.subtitleText)
             Spacer()
         }
     }
 
-    private var subtitleText: String {
-        if channel.isMuted {
-            return L10n.Channel.Item.muted
-        } else if shouldShowTypingIndicator {
-            return channel.typingIndicatorString(currentUserId: chatClient.currentUserId)
-        } else if let lastMessageText = channel.lastMessageText {
-            return lastMessageText
-        } else {
-            return L10n.Channel.Item.emptyMessages
-        }
-    }
-    
     private var shouldShowReadEvents: Bool {
         if let message = channel.latestMessages.first,
            message.isSentByCurrentUser,
@@ -110,26 +99,12 @@ public struct ChatChannelListItem: View {
         return false
     }
 
-    private var shouldShowTypingIndicator: Bool {
-        !channel.currentlyTypingUsersFiltered(
-            currentUserId: chatClient.currentUserId
-        ).isEmpty && channel.config.typingEventsEnabled
-    }
-    
     private var image: UIImage? {
         if channel.isMuted {
             return images.muted
         }
         return nil
     }
-    
-    private var timestampText: String {
-        if let lastMessageAt = channel.lastMessageAt {
-            return utils.dateFormatter.string(from: lastMessageAt)
-        } else {
-            return ""
-        }
-    }
 }
 
 /// View for the avatar used in channels (includes online indicator overlay).
@@ -206,6 +181,14 @@ public struct UnreadIndicatorView: View {
     }
 }
 
+public struct InjectedChannelInfo {
+    public var subtitle: String?
+    public var unreadCount: Int
+    public var timestamp: String?
+    public var lastMessageAt: Date?
+    public var latestMessages: [ChatMessage]?
+}
+
 extension ChatChannel {
 
     var lastMessageText: String? {
@@ -215,4 +198,30 @@ extension ChatChannel {
             return nil
         }
     }
+    
+    var shouldShowTypingIndicator: Bool {
+        !currentlyTypingUsersFiltered(
+            currentUserId: InjectedValues[\.chatClient].currentUserId
+        ).isEmpty && config.typingEventsEnabled
+    }
+    
+    var subtitleText: String {
+        if isMuted {
+            return L10n.Channel.Item.muted
+        } else if shouldShowTypingIndicator {
+            return typingIndicatorString(currentUserId: InjectedValues[\.chatClient].currentUserId)
+        } else if let lastMessageText = lastMessageText {
+            return lastMessageText
+        } else {
+            return L10n.Channel.Item.emptyMessages
+        }
+    }
+    
+    var timestampText: String {
+        if let lastMessageAt = lastMessageAt {
+            return InjectedValues[\.utils].dateFormatter.string(from: lastMessageAt)
+        } else {
+            return ""
+        }
+    }
 }

Sources/StreamChatSwiftUI/ChatChannelList/ChatChannelListViewModel.swift

@@ -38,10 +38,17 @@ open class ChatChannelListViewModel: ObservableObject, ChatChannelListController
     /// Checks if internet connection is available.
     private let networkReachability = NetworkReachability()
 
+    /// Checks if the queued changes are completely applied.
+    private var markDirty = false
+    
     /// Published variables.
     @Published public var channels = LazyCachedMapCollection<ChatChannel>() {
         didSet {
-            queuedChannelsChanges = []
+            if !markDirty {
+                queuedChannelsChanges = []
+            } else {
+                markDirty = false
+            }
         }
     }
 
@@ -355,6 +362,33 @@ open class ChatChannelListViewModel: ObservableObject, ChatChannelListController
     private func handleChannelAppearance() {
         if !queuedChannelsChanges.isEmpty && selectedChannel == nil && deeplinkChannel == nil {
             channels = queuedChannelsChanges
+        } else if !queuedChannelsChanges.isEmpty {
+            let selected = selectedChannel != nil ? selectedChannel?.channel : deeplinkChannel?.channel
+            var index: Int?
+            var temp = Array(queuedChannelsChanges)
+            for i in 0..<temp.count {
+                let current = temp[i]
+                if current.cid == selected?.cid {
+                    index = i
+                    selectedChannel?.injectedChannelInfo = InjectedChannelInfo(
+                        subtitle: current.subtitleText,
+                        unreadCount: 0,
+                        timestamp: current.timestampText,
+                        lastMessageAt: current.lastMessageAt,
+                        latestMessages: current.latestMessages
+                    )
+                    break
+                }
+            }
+            if let index = index, let selected = selected {
+                temp[index] = selected
+            }
+            markDirty = true
+            channels = LazyCachedMapCollection(source: temp, map: { $0 })
+        } else if queuedChannelsChanges.isEmpty && (selectedChannel != nil || deeplinkChannel != nil) {
+            if selectedChannel?.injectedChannelInfo == nil {
+                selectedChannel?.injectedChannelInfo = InjectedChannelInfo(unreadCount: 0)
+            }
         }
     }
 

Sources/StreamChatSwiftUI/ChatChannelList/ChatChannelNavigatableListItem.swift

@@ -42,6 +42,7 @@ public struct ChatChannelNavigatableListItem<ChannelDestination: View>: View {
             ChatChannelListItem(
                 channel: channel,
                 channelName: channelName,
+                injectedChannelInfo: injectedChannelInfo,
                 avatar: avatar,
                 onlineIndicatorShown: onlineIndicatorShown,
                 disabled: disabled,
@@ -59,6 +60,10 @@ public struct ChatChannelNavigatableListItem<ChannelDestination: View>: View {
         }
         .id("\(channel.id)-navigatable")
     }
+    
+    private var injectedChannelInfo: InjectedChannelInfo? {
+        selectedChannel?.channel.cid.rawValue == channel.cid.rawValue ? selectedChannel?.injectedChannelInfo : nil
+    }
 }
 
 /// Used for representing selection of an item in the channel list.
@@ -68,6 +73,7 @@ public struct ChannelSelectionInfo: Identifiable {
     public let id: String
     public let channel: ChatChannel
     public let message: ChatMessage?
+    public var injectedChannelInfo: InjectedChannelInfo?
 
     public init(channel: ChatChannel, message: ChatMessage?) {
         self.channel = channel

StreamChatSwiftUITests/Tests/ChatChannelList/ChatChannelListViewModel_Tests.swift

@@ -178,6 +178,62 @@ class ChatChannelListViewModel_Tests: StreamChatTestCase {
         XCTAssert(viewModel.channels.isEmpty)
     }
 
+    func test_channelListVM_queuedChangesUpdate() {
+        // Given
+        let channelId = ChannelId.unique
+        var channel = ChatChannel.mock(cid: channelId)
+        let channelListController = makeChannelListController(channels: [channel])
+        let viewModel = ChatChannelListViewModel(
+            channelListController: channelListController,
+            selectedChannelId: nil
+        )
+        viewModel.selectedChannel = ChannelSelectionInfo(channel: channel, message: nil)
+        channelListController.simulateInitial(channels: [channel], state: .remoteDataFetched)
+        
+        // When
+        let message = ChatMessage.mock(
+            id: .unique,
+            cid: channelId,
+            text: "Test message",
+            author: .mock(id: .unique, name: "Martin")
+        )
+        channel = ChatChannel.mock(cid: channelId, unreadCount: .mock(messages: 1), latestMessages: [message])
+        channelListController.simulate(
+            channels: [channel],
+            changes: [.update(channel, index: .init(row: 0, section: 0))]
+        )
+        viewModel.checkForChannels(index: 0)
+        
+        // Then
+        let injectedChannelInfo = viewModel.selectedChannel?.injectedChannelInfo!
+        let presentedSubtitle = injectedChannelInfo!.subtitle!
+        let unreadCount = injectedChannelInfo!.unreadCount
+        XCTAssert(presentedSubtitle == channel.subtitleText)
+        XCTAssert(viewModel.channels[0].subtitleText == "No messages")
+        XCTAssert(unreadCount == 0)
+        XCTAssert(channel.shouldShowTypingIndicator == false)
+    }
+    
+    func test_channelListVM_badgeCountUpdate() {
+        // Given
+        let channelId = ChannelId.unique
+        let channel = ChatChannel.mock(cid: channelId, unreadCount: .mock(messages: 1))
+        let channelListController = makeChannelListController(channels: [channel])
+        let viewModel = ChatChannelListViewModel(
+            channelListController: channelListController,
+            selectedChannelId: nil
+        )
+        viewModel.selectedChannel = ChannelSelectionInfo(channel: channel, message: nil)
+        
+        // When
+        viewModel.checkForChannels(index: 0)
+        
+        // Then
+        let injectedChannelInfo = viewModel.selectedChannel?.injectedChannelInfo!
+        let unreadCount = injectedChannelInfo!.unreadCount
+        XCTAssert(unreadCount == 0)
+    }
+    
     // MARK: - private
 
     private func makeChannelListController(