ios: optimise mark-as-read performance (#4434)

* ios: optimise mark-as-read rendering performance

* merge master

* minor

* make chat observable

* make model EnvironmentObject

---------

Co-authored-by: Evgeny Poberezkin <evgeny@poberezkin.com>

apps/ios/Shared/Model/ChatModel.swift

@@ -74,6 +74,7 @@ final class ChatModel: ObservableObject {
     @Published var chatToTop: String?
     @Published var groupMembers: [GMember] = []
     @Published var groupMembersIndexes: Dictionary<Int64, Int> = [:] // groupMemberId to index in groupMembers list
+    @Published var membersLoaded = false
     // items in the terminal view
     @Published var showingTerminal = false
     @Published var terminalItems: [TerminalItem] = []
@@ -195,6 +196,18 @@ final class ChatModel: ObservableObject {
         return nil
     }
 
+    func loadGroupMembers(_ groupInfo: GroupInfo, updateView: @escaping () -> Void = {}) async {
+        let groupMembers = await apiListMembers(groupInfo.groupId)
+        await MainActor.run {
+            if chatId == groupInfo.id {
+                self.groupMembers = groupMembers.map { GMember.init($0) }
+                self.populateGroupMembersIndexes()
+                self.membersLoaded = true
+                updateView()
+            }
+        }
+    }
+
     private func getChatIndex(_ id: String) -> Int? {
         chats.firstIndex(where: { $0.id == id })
     }
@@ -390,8 +403,8 @@ final class ChatModel: ObservableObject {
     }
 
     func removeChatItem(_ cInfo: ChatInfo, _ cItem: ChatItem) {
-        if cItem.isRcvNew {
-            decreaseUnreadCounter(cInfo)
+        if cItem.isRcvNew, let chatIndex = getChatIndex(cInfo.id) {
+            decreaseUnreadCounter(chatIndex)
         }
         // update previews
         if let chat = getChat(cInfo.id) {
@@ -536,13 +549,18 @@ final class ChatModel: ObservableObject {
         }
     }
 
-    func markChatItemRead(_ cInfo: ChatInfo, _ cItem: ChatItem) {
-        if chatId == cInfo.id, let i = getChatItemIndex(cItem) {
-            if reversedChatItems[i].isRcvNew {
-                // update current chat
-                markChatItemRead_(i)
-                // update preview
-                decreaseUnreadCounter(cInfo)
+    func markChatItemRead(_ cInfo: ChatInfo, _ cItem: ChatItem) async {
+        if chatId == cInfo.id,
+           let itemIndex = getChatItemIndex(cItem),
+           let chatIndex = getChatIndex(cInfo.id),
+           reversedChatItems[itemIndex].isRcvNew {
+            await MainActor.run {
+                withTransaction(Transaction()) {
+                    // update current chat
+                    markChatItemRead_(itemIndex)
+                    // update preview
+                    decreaseUnreadCounter(chatIndex)
+                }
             }
         }
     }
@@ -558,11 +576,9 @@ final class ChatModel: ObservableObject {
         }
     }
 
-    func decreaseUnreadCounter(_ cInfo: ChatInfo) {
-        if let i = getChatIndex(cInfo.id) {
-            chats[i].chatStats.unreadCount = chats[i].chatStats.unreadCount - 1
-            decreaseUnreadCounter(user: currentUser!)
-        }
+    func decreaseUnreadCounter(_ chatIndex: Int) {
+        chats[chatIndex].chatStats.unreadCount = chats[chatIndex].chatStats.unreadCount - 1
+        decreaseUnreadCounter(user: currentUser!)
     }
 
     func increaseUnreadCounter(user: any UserLike) {

apps/ios/Shared/Model/SimpleXAPI.swift

@@ -1207,7 +1207,7 @@ func apiMarkChatItemRead(_ cInfo: ChatInfo, _ cItem: ChatItem) async {
     do {
         logger.debug("apiMarkChatItemRead: \(cItem.id)")
         try await apiChatRead(type: cInfo.chatType, id: cInfo.apiId, itemRange: (cItem.id, cItem.id))
-        await MainActor.run { ChatModel.shared.markChatItemRead(cInfo, cItem) }
+        await ChatModel.shared.markChatItemRead(cInfo, cItem)
     } catch {
         logger.error("apiMarkChatItemRead apiChatRead error: \(responseError(error))")
     }

apps/ios/Shared/Views/Chat/ChatView.swift

@@ -37,7 +37,6 @@ struct ChatView: View {
     @State private var searchText: String = ""
     @FocusState private var searchFocussed
     // opening GroupMemberInfoView on member icon
-    @State private var membersLoaded = false
     @State private var selectedMember: GMember? = nil
     // opening GroupLinkView on link button (incognito)
     @State private var showGroupLinkSheet: Bool = false
@@ -122,7 +121,7 @@ struct ChatView: View {
                         chatModel.reversedChatItems = []
                         chatModel.groupMembers = []
                         chatModel.groupMembersIndexes.removeAll()
-                        membersLoaded = false
+                        chatModel.membersLoaded = false
                     }
                 }
             }
@@ -164,7 +163,7 @@ struct ChatView: View {
                     }
                 } else if case let .group(groupInfo) = cInfo {
                     Button {
-                        Task { await loadGroupMembers(groupInfo) { showChatInfoSheet = true } }
+                        Task { await chatModel.loadGroupMembers(groupInfo) { showChatInfoSheet = true } }
                     } label: {
                         ChatInfoToolbar(chat: chat)
                             .tint(theme.colors.primary)
@@ -250,19 +249,7 @@ struct ChatView: View {
             }
         }
     }
-
-    private func loadGroupMembers(_ groupInfo: GroupInfo, updateView: @escaping () -> Void = {}) async {
-        let groupMembers = await apiListMembers(groupInfo.groupId)
-        await MainActor.run {
-            if chatModel.chatId == groupInfo.id {
-                chatModel.groupMembers = groupMembers.map { GMember.init($0) }
-                chatModel.populateGroupMembersIndexes()
-                membersLoaded = true
-                updateView()
-            }
-        }
-    }
-
+    
     private func initChatView() {
         let cInfo = chat.chatInfo
         // This check prevents the call to apiContactInfo after the app is suspended, and the database is closed.
@@ -477,9 +464,7 @@ struct ChatView: View {
                         .foregroundColor(theme.colors.primary)
                 }
                 .onTapGesture {
-                    if let latestUnreadItem = filtered(chatModel.reversedChatItems).last(where: { $0.isRcvNew }) {
-                        scrollModel.scrollToItem(id: latestUnreadItem.id)
-                    }
+                    scrollModel.scrollToBottom()
                 }
             } else if !counts.isNearBottom {
                 circleButton {
@@ -534,7 +519,7 @@ struct ChatView: View {
     private func addMembersButton() -> some View {
         Button {
             if case let .group(gInfo) = chat.chatInfo {
-                Task { await loadGroupMembers(gInfo) { showAddMembersSheet = true } }
+                Task { await chatModel.loadGroupMembers(gInfo) { showAddMembersSheet = true } }
             }
         } label: {
             Image(systemName: "person.crop.circle.badge.plus")
@@ -604,11 +589,9 @@ struct ChatView: View {
             chat: chat,
             chatItem: ci,
             maxWidth: maxWidth,
-            itemWidth: maxWidth,
             composeState: $composeState,
             selectedMember: $selectedMember,
-            revealedChatItem: $revealedChatItem,
-            chatView: self
+            revealedChatItem: $revealedChatItem
         )
     }
 
@@ -616,13 +599,11 @@ struct ChatView: View {
         @EnvironmentObject var m: ChatModel
         @EnvironmentObject var theme: AppTheme
         @ObservedObject var chat: Chat
-        var chatItem: ChatItem
-        var maxWidth: CGFloat
-        @State var itemWidth: CGFloat
+        let chatItem: ChatItem
+        let maxWidth: CGFloat
         @Binding var composeState: ComposeState
         @Binding var selectedMember: GMember?
         @Binding var revealedChatItem: ChatItem?
-        var chatView: ChatView
 
         @State private var deletingItem: ChatItem? = nil
         @State private var showDeleteMessage = false
@@ -700,11 +681,11 @@ struct ChatView: View {
                         HStack(alignment: .top, spacing: 8) {
                             ProfileImage(imageStr: member.memberProfile.image, size: memberImageSize, backgroundColor: theme.colors.background)
                                 .onTapGesture {
-                                    if chatView.membersLoaded {
+                                    if m.membersLoaded {
                                         selectedMember = m.getGroupMember(member.groupMemberId)
                                     } else {
                                         Task {
-                                            await chatView.loadGroupMembers(groupInfo) {
+                                            await m.loadGroupMembers(groupInfo) {
                                                 selectedMember = m.getGroupMember(member.groupMemberId)
                                             }
                                         }
@@ -1099,7 +1080,7 @@ struct ChatView: View {
                             chatItemInfo = ciInfo
                         }
                         if case let .group(gInfo) = chat.chatInfo {
-                            await chatView.loadGroupMembers(gInfo)
+                            await m.loadGroupMembers(gInfo)
                         }
                     } catch let error {
                         logger.error("apiGetChatItemInfo error: \(responseError(error))")