fix(crash): introduced throttling for UI updates to avoid UI freeze (#8)

* fix(freeze): introduce throttler to updating UI to avoid crashes

Enchanted.xcodeproj/project.pbxproj

@@ -35,6 +35,7 @@
 		FF10027A2B27B6070011A4DC /* MarkdownUI in Frameworks */ = {isa = PBXBuildFile; productRef = FF1002792B27B6070011A4DC /* MarkdownUI */; };
 		FF5FA0D62B35169400BC471D /* Binding+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = FF5FA0D52B35169400BC471D /* Binding+Extension.swift */; };
 		FF61C9632B2A7DC6003CD1CB /* OllamaKit in Frameworks */ = {isa = PBXBuildFile; productRef = FF61C9622B2A7DC6003CD1CB /* OllamaKit */; };
+		FF6B7B132B3EE7AC00E8FEA3 /* Throttler.swift in Sources */ = {isa = PBXBuildFile; fileRef = FF6B7B122B3EE7AC00E8FEA3 /* Throttler.swift */; };
 		FFB0327D2B312F3D0066A9DB /* RecordingView.swift in Sources */ = {isa = PBXBuildFile; fileRef = FFB0327C2B312F3D0066A9DB /* RecordingView.swift */; };
 		FFBBF4842B34881B008D611C /* SpeechRecogniser.swift in Sources */ = {isa = PBXBuildFile; fileRef = FFBBF4832B34881B008D611C /* SpeechRecogniser.swift */; };
 		FFBBF4882B34F9C8008D611C /* View+Extension.swift in Sources */ = {isa = PBXBuildFile; fileRef = FFBBF4872B34F9C8008D611C /* View+Extension.swift */; };
@@ -74,6 +75,7 @@
 		FF1002722B276EC10011A4DC /* AppColorScheme.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppColorScheme.swift; sourceTree = "<group>"; };
 		FF1002742B278C170011A4DC /* AppStore.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppStore.swift; sourceTree = "<group>"; };
 		FF5FA0D52B35169400BC471D /* Binding+Extension.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Binding+Extension.swift"; sourceTree = "<group>"; };
+		FF6B7B122B3EE7AC00E8FEA3 /* Throttler.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Throttler.swift; sourceTree = "<group>"; };
 		FFB0327C2B312F3D0066A9DB /* RecordingView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RecordingView.swift; sourceTree = "<group>"; };
 		FFBBF4822B348345008D611C /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist; path = Info.plist; sourceTree = "<group>"; };
 		FFBBF4832B34881B008D611C /* SpeechRecogniser.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SpeechRecogniser.swift; sourceTree = "<group>"; };
@@ -263,6 +265,7 @@
 				FF10023D2B24F4900011A4DC /* OllamaService.swift */,
 				FF10024F2B25C79F0011A4DC /* SwiftDataService.swift */,
 				FF0146CC2B3DADCA00A2A9F6 /* HapticsService.swift */,
+				FF6B7B122B3EE7AC00E8FEA3 /* Throttler.swift */,
 			);
 			path = Services;
 			sourceTree = "<group>";
@@ -391,6 +394,7 @@
 				FF1002392B24BBF20011A4DC /* Chat.swift in Sources */,
 				FFB0327D2B312F3D0066A9DB /* RecordingView.swift in Sources */,
 				FF10024A2B25BE740011A4DC /* LanguageModelSD.swift in Sources */,
+				FF6B7B132B3EE7AC00E8FEA3 /* Throttler.swift in Sources */,
 				FF1002402B24F7320011A4DC /* SideBarMenuView.swift in Sources */,
 				FFBBF4882B34F9C8008D611C /* View+Extension.swift in Sources */,
 				FFBBF4842B34881B008D611C /* SpeechRecogniser.swift in Sources */,
@@ -564,7 +568,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "@executable_path/Frameworks";
 				"LD_RUNPATH_SEARCH_PATHS[sdk=macosx*]" = "@executable_path/../Frameworks";
 				MACOSX_DEPLOYMENT_TARGET = 14.0;
-				MARKETING_VERSION = 1.2.0;
+				MARKETING_VERSION = 1.2.1;
 				PRODUCT_BUNDLE_IDENTIFIER = subj.Enchanted;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = auto;
@@ -609,7 +613,7 @@
 				LD_RUNPATH_SEARCH_PATHS = "@executable_path/Frameworks";
 				"LD_RUNPATH_SEARCH_PATHS[sdk=macosx*]" = "@executable_path/../Frameworks";
 				MACOSX_DEPLOYMENT_TARGET = 14.0;
-				MARKETING_VERSION = 1.2.0;
+				MARKETING_VERSION = 1.2.1;
 				PRODUCT_BUNDLE_IDENTIFIER = subj.Enchanted;
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SDKROOT = auto;

Enchanted.xcodeproj/xcuserdata/wpc.xcuserdatad/xcdebugger/Breakpoints_v2.xcbkptlist

@@ -3,38 +3,4 @@
    uuid = "F86A12CB-2FB3-442A-8D63-13A618A57A08"
    type = "1"
    version = "2.0">
-   <Breakpoints>
-      <BreakpointProxy
-         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
-         <BreakpointContent
-            uuid = "94A85A32-A41A-49F5-8A96-8582F50E6F3A"
-            shouldBeEnabled = "Yes"
-            ignoreCount = "0"
-            continueAfterRunningActions = "No"
-            filePath = "Enchanted/UI/Views/Sidebar/SidebarView.swift"
-            startingColumnNumber = "9223372036854775807"
-            endingColumnNumber = "9223372036854775807"
-            startingLineNumber = "5"
-            endingLineNumber = "5"
-            landmarkName = "unknown"
-            landmarkType = "0">
-         </BreakpointContent>
-      </BreakpointProxy>
-      <BreakpointProxy
-         BreakpointExtensionID = "Xcode.Breakpoint.FileBreakpoint">
-         <BreakpointContent
-            uuid = "93592730-88C1-4814-A19F-6389E78CABAE"
-            shouldBeEnabled = "No"
-            ignoreCount = "0"
-            continueAfterRunningActions = "No"
-            filePath = "Enchanted/UI/Views/Settings/SettingsView.swift"
-            startingColumnNumber = "9223372036854775807"
-            endingColumnNumber = "9223372036854775807"
-            startingLineNumber = "15"
-            endingLineNumber = "15"
-            landmarkName = "SettingsView"
-            landmarkType = "14">
-         </BreakpointContent>
-      </BreakpointProxy>
-   </Breakpoints>
 </Bucket>

Enchanted/Services/Throttler.swift

@@ -0,0 +1,33 @@
+//
+//  Throttler.swift
+//  Enchanted
+//
+//  Created by Augustinas Malinauskas on 29/12/2023.
+//
+
+import Foundation
+
+class Throttler {
+    private var workItem: DispatchWorkItem?
+    private var lastRun: Date = .distantPast
+    private let queue: DispatchQueue
+    private let delay: TimeInterval
+
+    init(delay: TimeInterval, queue: DispatchQueue = DispatchQueue.main) {
+        self.delay = delay
+        self.queue = queue
+    }
+
+    func throttle(_ block: @escaping () -> Void) {
+        workItem?.cancel()
+
+        let item = DispatchWorkItem { [weak self] in
+            self?.lastRun = Date()
+            block()
+        }
+        self.workItem = item
+
+        let delayFactor = Date().timeIntervalSince(lastRun) >= delay ? 0 : delay
+        queue.asyncAfter(deadline: .now() + delayFactor, execute: item)
+    }
+}

Enchanted/Stores/ConversationStore.swift

@@ -16,10 +16,15 @@ final class ConversationStore {
     private var swiftDataService: SwiftDataService
     private var generation: AnyCancellable?
 
+    /// For some reason (SwiftUI bug / too frequent UI updates) updating UI for each stream message sometimes freezes the UI.
+    /// Throttling UI updates seem to fix the issue.
+    private var currentMessageBuffer: String = ""
+    private let throttler = Throttler(delay: 0.25)
+
     var conversationState: ConversationState = .completed
     var conversations: [ConversationSD] = []
     var selectedConversation: ConversationSD?
-    var messages: [MessageSD] = []
+    @MainActor var messages: [MessageSD] = []
 
     init(swiftDataService: SwiftDataService) {
         self.swiftDataService = swiftDataService
@@ -36,12 +41,12 @@ final class ConversationStore {
         try swiftDataService.createConversation(conversation)
     }
 
-    func reloadConversation(_ conversation: ConversationSD) throws {
+    @MainActor func reloadConversation(_ conversation: ConversationSD) throws {
         selectedConversation = try swiftDataService.getConversation(conversation.id)
         messages = try swiftDataService.fetchMessages(conversation.id)
     }
 
-    func selectConversation(_ conversation: ConversationSD) throws {
+    @MainActor func selectConversation(_ conversation: ConversationSD) throws {
         try reloadConversation(conversation)
     }
 
@@ -50,8 +55,8 @@ final class ConversationStore {
         conversations = try swiftDataService.fetchConversations()
     }
 
-//    @MainActor 
-    func stopGenerate() {
+    //    @MainActor
+    @MainActor func stopGenerate() {
         generation?.cancel()
         handleComplete()
         withAnimation {
@@ -75,11 +80,11 @@ final class ConversationStore {
 
         let userMessage = MessageSD(content: userPrompt, role: "user", image: image?.render()?.compressImageData())
         userMessage.conversation = conversation
-
+        
         var messageHistory = conversation.messages
             .sorted{$0.createdAt < $1.createdAt}
             .map{ChatMessage(role: $0.role, content: $0.content)
-        }
+            }
 
         /// attach selected image to the last Message
         if let lastMessage = messageHistory.popLast() {
@@ -112,7 +117,7 @@ final class ConversationStore {
                         case .finished:
                             self?.handleComplete()
                         case .failure(let error):
-                             self?.handleError(error.localizedDescription)
+                            self?.handleError(error.localizedDescription)
                         }
                     }, receiveValue: { [weak self] response in
                         self?.handleReceive(response)
@@ -123,38 +128,46 @@ final class ConversationStore {
         }
     }
 
-//    @MainActor
+    @MainActor
     private func handleReceive(_ response: OKChatResponse)  {
-        DispatchQueue.main.async { [self] in
-            if messages.isEmpty { return }
+        if messages.isEmpty { return }
+
+        if let responseContent = response.message?.content {
+            currentMessageBuffer = currentMessageBuffer + responseContent
 
-            let lastIndex = messages.count - 1
-            let currentContent = messages[lastIndex].content
-
-            if let responseContent = response.message?.content {
-                messages[lastIndex].content = currentContent + responseContent
+            throttler.throttle { [weak self] in
+                guard let self = self else { return }
+                let lastIndex = self.messages.count - 1
+                self.messages[lastIndex].content.append(currentMessageBuffer)
+                currentMessageBuffer = ""
             }
-            conversationState = .loading
         }
     }
 
-//    @MainActor
+        @MainActor
     private func handleError(_ errorMessage: String) {
         guard let lastMesasge = messages.last else { return }
         lastMesasge.error = true
         lastMesasge.done = false
-        try? swiftDataService.updateMessage(lastMesasge)
+
+        Task(priority: .background) {
+            try? swiftDataService.updateMessage(lastMesasge)
+        }
+
         withAnimation {
             conversationState = .error(message: errorMessage)
         }
     }
 
-//    @MainActor
+        @MainActor
     private func handleComplete() {
         guard let lastMesasge = messages.last else { return }
         lastMesasge.error = false
         lastMesasge.done = true
-        try? swiftDataService.updateMessage(lastMesasge)
+
+        Task(priority: .background) {
+            try self.swiftDataService.updateMessage(lastMesasge)
+        }
 
         withAnimation {
             conversationState = .completed

Enchanted/UI/Views/Chat/Chat.swift

@@ -28,21 +28,16 @@ struct Chat: View {
 
     func onConversationTap(_ conversation: ConversationSD) {
         withAnimation(.bouncy(duration: 0.3)) {
-            do {
-                try conversationStore.selectConversation(conversation)
-                Task {
-                    await languageModelStore.setModel(model: conversation.model)
-                }
-            } catch {
-
+            Task {
+                try await conversationStore.selectConversation(conversation)
+                await languageModelStore.setModel(model: conversation.model)
             }
             showMenu.toggle()
         }
         Haptics.shared.play(.medium)
     }
 
-//    @MainActor 
-    func onStopGenerateTap() {
+    @MainActor func onStopGenerateTap() {
         conversationStore.stopGenerate()
         Haptics.shared.play(.medium)
     }