Refactor starting new chat

FirebaseVertexAI/Sample/ChatSample/Screens/ConversationScreen.swift

@@ -104,7 +104,9 @@ struct ConversationScreen: View {
   }
 
   private func newChat() {
-    viewModel.startNewChat()
+    Task {
+      await viewModel.startNewChat()
+    }
   }
 }
 

FirebaseVertexAI/Sample/ChatSample/ViewModels/ConversationViewModel.swift

@@ -21,8 +21,8 @@ class ConversationViewModel: ObservableObject {
   /// This array holds both the user's and the system's chat messages
   @Published var messages = [ChatMessage]()
 
-  /// Indicates we're waiting for the model to finish
-  @Published var busy = false
+  /// Indicates we're waiting for the model to finish or the UI is loading
+  @Published var busy = true
 
   @Published var error: Error?
   var hasError: Bool {
@@ -37,25 +37,28 @@ class ConversationViewModel: ObservableObject {
 
   init() {
     model = VertexAI.vertexAI().generativeModel(modelName: "gemini-1.5-flash")
+    Task {
+      await startNewChat()
+    }
   }
 
   func sendMessage(_ text: String, streaming: Bool = true) async {
-    error = nil
-    if chat == nil {
-      chat = await model.startChat()
-    }
+    stop()
     if streaming {
       await internalSendMessageStreaming(text)
     } else {
       await internalSendMessage(text)
     }
   }
 
-  func startNewChat() {
+  func startNewChat() async {
+    busy = true
+    defer {
+      busy = false
+    }
     stop()
-    error = nil
-    chat = nil
     messages.removeAll()
+    chat = await model.startChat()
   }
 
   func stop() {
@@ -64,8 +67,6 @@ class ConversationViewModel: ObservableObject {
   }
 
   private func internalSendMessageStreaming(_ text: String) async {
-    chatTask?.cancel()
-
     chatTask = Task {
       busy = true
       defer {
@@ -100,8 +101,6 @@ class ConversationViewModel: ObservableObject {
   }
 
   private func internalSendMessage(_ text: String) async {
-    chatTask?.cancel()
-
     chatTask = Task {
       busy = true
       defer {

FirebaseVertexAI/Sample/FunctionCallingSample/Screens/FunctionCallingScreen.swift

@@ -106,7 +106,9 @@ struct FunctionCallingScreen: View {
   }
 
   private func newChat() {
-    viewModel.startNewChat()
+    Task {
+      await viewModel.startNewChat()
+    }
   }
 }
 

FirebaseVertexAI/Sample/FunctionCallingSample/ViewModels/FunctionCallingViewModel.swift

@@ -62,22 +62,19 @@ class FunctionCallingViewModel: ObservableObject {
         ),
       ])]
     )
+    Task {
+      await startNewChat()
+    }
   }
 
   func sendMessage(_ text: String, streaming: Bool = true) async {
-    error = nil
-    chatTask?.cancel()
-
+    stop()
     chatTask = Task {
       busy = true
       defer {
         busy = false
       }
 
-      if chat == nil {
-        chat = await model.startChat()
-      }
-
       // first, add the user's message to the chat
       let userMessage = ChatMessage(message: text, participant: .user)
       messages.append(userMessage)
@@ -103,11 +100,14 @@ class FunctionCallingViewModel: ObservableObject {
     }
   }
 
-  func startNewChat() {
+  func startNewChat() async {
+    busy = true
+    defer {
+      busy = false
+    }
     stop()
-    error = nil
-    chat = nil
     messages.removeAll()
+    chat = await model.startChat()
   }
 
   func stop() {