Add Speech to Text service

This commit adds Speech to Text capabilities to the chat application. In particular, it streams microphone audio to the Speech to Text service when the microphone button is touched. Interim transcription results from the service are used to set the text field as they are received. Streaming ends when the microphone button is released by the user.

ChatApp/ChatApp/ViewController.m

@@ -22,6 +22,7 @@ @interface ViewController ()
 @property (strong, nonatomic) Messages *messages;
 @property (strong, nonatomic) ConversationBridge *conversation;
 @property (strong, nonatomic) TextToSpeechBridge *textToSpeech;
+@property (strong, nonatomic) SpeechToTextBridge *speechToText;
 
 @end
 
@@ -45,9 +46,13 @@ - (void)viewDidLoad
     [microphoneButton setImage:microphoneImage forState:UIControlStateNormal];
     microphoneButton.imageView.contentMode = UIViewContentModeScaleAspectFit;
     self.inputToolbar.contentView.leftBarButtonItem = microphoneButton;
+
+    [microphoneButton addTarget:self action:@selector(didPressMicrophoneButton:) forControlEvents:UIControlEventTouchDown];
+    [microphoneButton addTarget:self action:@selector(didReleaseMicrophoneButton:) forControlEvents:UIControlEventTouchUpInside];
 
     self.conversation = [[ConversationBridge alloc] init];
     self.textToSpeech = [[TextToSpeechBridge alloc] init];
+    self.speechToText = [[SpeechToTextBridge alloc] init];
 
     [self.conversation startConversation:nil success:^(NSString *response){
         [self didReceiveConversationResponse:response];
@@ -70,6 +75,19 @@ - (void)didReceiveConversationResponse:(NSString *)response
     [self.textToSpeech synthesize:response];
 }
 
+- (void)didPressMicrophoneButton:(UIButton *)sender
+{
+    [self.speechToText startTranscribing:^(NSString *transcript) {
+        self.inputToolbar.contentView.textView.text = transcript;
+        [self.inputToolbar toggleSendButtonEnabled];
+    }];
+}
+
+- (void)didReleaseMicrophoneButton:(UIButton *)sender
+{
+    [self.speechToText stopTranscribing:nil];
+}
+
 #pragma mark - Custom menu actions for cells
 
 - (void)didReceiveMenuWillShowNotification:(NSNotification *)notification

ChatApp/ChatApp/WatsonBridge.swift

@@ -18,6 +18,7 @@ import Foundation
 import AVFoundation
 import TextToSpeechV1
 import ConversationV1
+import SpeechToTextV1
 
 class TextToSpeechBridge: NSObject {
 
@@ -61,3 +62,31 @@ class ConversationBridge: NSObject {
         }
     }
 }
+
+class SpeechToTextBridge: NSObject {
+
+    private var stopStreaming: SpeechToText.StopStreaming?
+    private let speechToText = SpeechToText(
+        username: credentials["SpeechToTextUsername"]!,
+        password: credentials["SpeechToTextPassword"]!
+    )
+
+    func startTranscribing(success: (String -> Void)) {
+        var settings = TranscriptionSettings(contentType: .L16(rate: 44100, channels: 1))
+        settings.continuous = false
+        settings.interimResults = true
+
+        let failure = { (error: NSError) in print(error) }
+        stopStreaming = speechToText.transcribe(settings, failure: failure) { results in
+            if let transcript = results.last?.alternatives.last?.transcript {
+                success(transcript)
+            }
+        }
+    }
+
+    func stopTranscribing(success: (Void -> Void)? = nil) {
+        stopStreaming?()
+        stopStreaming = nil
+        success?()
+    }
+}