Update sample apps

Author: andrewheard

FirebaseVertexAI/Sample/ChatSample/ViewModels/ConversationViewModel.swift

@@ -30,17 +30,19 @@ class ConversationViewModel: ObservableObject {
   }
 
   private var model: GenerativeModel
-  private var chat: Chat
+  private var chat: Chat? = nil
   private var stopGenerating = false
 
   private var chatTask: Task<Void, Never>?
 
   init() {
     model = VertexAI.vertexAI().generativeModel(modelName: "gemini-1.5-flash")
-    chat = model.startChat()
   }
 
   func sendMessage(_ text: String, streaming: Bool = true) async {
+    if chat == nil {
+      chat = await model.startChat()
+    }
     error = nil
     if streaming {
       await internalSendMessageStreaming(text)
@@ -52,7 +54,7 @@ class ConversationViewModel: ObservableObject {
   func startNewChat() {
     stop()
     error = nil
-    chat = model.startChat()
+    chat = nil
     messages.removeAll()
   }
 
@@ -79,7 +81,10 @@ class ConversationViewModel: ObservableObject {
       messages.append(systemMessage)
 
       do {
-        let responseStream = chat.sendMessageStream(text)
+        guard let chat else {
+          throw ChatError.notInitialized
+        }
+        let responseStream = try await chat.sendMessageStream(text)
         for try await chunk in responseStream {
           messages[messages.count - 1].pending = false
           if let text = chunk.text {
@@ -112,10 +117,12 @@ class ConversationViewModel: ObservableObject {
       messages.append(systemMessage)
 
       do {
-        var response: GenerateContentResponse?
-        response = try await chat.sendMessage(text)
+        guard let chat = chat else {
+          throw ChatError.notInitialized
+        }
+        let response = try await chat.sendMessage(text)
 
-        if let responseText = response?.text {
+        if let responseText = response.text {
           // replace pending message with backend response
           messages[messages.count - 1].message = responseText
           messages[messages.count - 1].pending = false
@@ -127,4 +134,8 @@ class ConversationViewModel: ObservableObject {
       }
     }
   }
+
+  enum ChatError: Error {
+    case notInitialized
+  }
 }

FirebaseVertexAI/Sample/FunctionCallingSample/ViewModels/FunctionCallingViewModel.swift

@@ -33,7 +33,7 @@ class FunctionCallingViewModel: ObservableObject {
   private var functionCalls = [FunctionCall]()
 
   private var model: GenerativeModel
-  private var chat: Chat
+  private var chat: Chat? = nil
 
   private var chatTask: Task<Void, Never>?
 
@@ -62,7 +62,6 @@ class FunctionCallingViewModel: ObservableObject {
         ),
       ])]
     )
-    chat = model.startChat()
   }
 
   func sendMessage(_ text: String, streaming: Bool = true) async {
@@ -75,6 +74,10 @@ class FunctionCallingViewModel: ObservableObject {
         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)
@@ -103,7 +106,7 @@ class FunctionCallingViewModel: ObservableObject {
   func startNewChat() {
     stop()
     error = nil
-    chat = model.startChat()
+    chat = nil
     messages.removeAll()
   }
 
@@ -114,14 +117,17 @@ class FunctionCallingViewModel: ObservableObject {
 
   private func internalSendMessageStreaming(_ text: String) async throws {
     let functionResponses = try await processFunctionCalls()
+    guard let chat else {
+      throw ChatError.notInitialized
+    }
     let responseStream: AsyncThrowingStream<GenerateContentResponse, Error>
     if functionResponses.isEmpty {
-      responseStream = chat.sendMessageStream(text)
+      responseStream = try await chat.sendMessageStream(text)
     } else {
       for functionResponse in functionResponses {
         messages.insert(functionResponse.chatMessage(), at: messages.count - 1)
       }
-      responseStream = chat.sendMessageStream(functionResponses.modelContent())
+      responseStream = try await chat.sendMessageStream(functionResponses.modelContent())
     }
     for try await chunk in responseStream {
       processResponseContent(content: chunk)
@@ -130,6 +136,9 @@ class FunctionCallingViewModel: ObservableObject {
 
   private func internalSendMessage(_ text: String) async throws {
     let functionResponses = try await processFunctionCalls()
+    guard let chat else {
+      throw ChatError.notInitialized
+    }
     let response: GenerateContentResponse
     if functionResponses.isEmpty {
       response = try await chat.sendMessage(text)
@@ -181,6 +190,10 @@ class FunctionCallingViewModel: ObservableObject {
     return functionResponses
   }
 
+  enum ChatError: Error {
+    case notInitialized
+  }
+
   // MARK: - Callable Functions
 
   func getExchangeRate(args: JSONObject) -> JSONObject {

FirebaseVertexAI/Sample/GenerativeAIMultimodalSample/ViewModels/PhotoReasoningViewModel.swift

@@ -84,7 +84,7 @@ class PhotoReasoningViewModel: ObservableObject {
         }
       }
 
-      let outputContentStream = model.generateContentStream(prompt, images)
+      let outputContentStream = try await model.generateContentStream(prompt, images)
 
       // stream response
       for try await outputContent in outputContentStream {

FirebaseVertexAI/Sample/GenerativeAITextSample/ViewModels/SummarizeViewModel.swift

@@ -50,7 +50,7 @@ class SummarizeViewModel: ObservableObject {
 
       let prompt = "Summarize the following text for me: \(inputText)"
 
-      let outputContentStream = model.generateContentStream(prompt)
+      let outputContentStream = try await model.generateContentStream(prompt)
 
       // stream response
       for try await outputContent in outputContentStream {