Fix lock behavior on RTCAudioSession.

webrtc/examples/objc/AppRTCDemo/ios/ARDVideoCallViewController.m

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #import "ARDVideoCallViewController.h"
 
+#import "webrtc/base/objc/RTCDispatcher.h"
+#import "webrtc/modules/audio_device/ios/objc/RTCAudioSession.h"
+
 #import "RTCAVFoundationVideoSource.h"
 #import "RTCLogging.h"
 
 #import "ARDAppClient.h"
 #import "ARDVideoCallView.h"
 
 @interface ARDVideoCallViewController () <ARDAppClientDelegate,
     ARDVideoCallViewDelegate>
 @property(nonatomic, strong) RTCVideoTrack *localVideoTrack;
 @property(nonatomic, strong) RTCVideoTrack *remoteVideoTrack;
 @property(nonatomic, readonly) ARDVideoCallView *videoCallView;
 @end
 
 @implementation ARDVideoCallViewController {
   ARDAppClient *_client;
   RTCVideoTrack *_remoteVideoTrack;
   RTCVideoTrack *_localVideoTrack;
+  AVAudioSessionPortOverride _portOverride;
 }
 
 @synthesize videoCallView = _videoCallView;
 
 - (instancetype)initForRoom:(NSString *)room
                  isLoopback:(BOOL)isLoopback
                 isAudioOnly:(BOOL)isAudioOnly {
   if (self = [super init]) {
     _client = [[ARDAppClient alloc] initWithDelegate:self];
     [_client connectToRoomWithId:room
@@ skipping 70 matching lines @@
 - (void)videoCallViewDidHangup:(ARDVideoCallView *)view {
   [self hangup];
 }
 
 - (void)videoCallViewDidSwitchCamera:(ARDVideoCallView *)view {
   // TODO(tkchin): Rate limit this so you can't tap continously on it.
   // Probably through an animation.
   [self switchCamera];
 }
 
+- (void)videoCallViewDidChangeRoute:(ARDVideoCallView *)view {
+  AVAudioSessionPortOverride override = AVAudioSessionPortOverrideNone;
+  if (_portOverride == AVAudioSessionPortOverrideNone) {
+    override = AVAudioSessionPortOverrideSpeaker;
+  }
+  [RTCDispatcher dispatchAsyncOnType:RTCDispatcherTypeAudioSession
+                               block:^{
+    RTCAudioSession *session = [RTCAudioSession sharedInstance];
+    [session lockForConfiguration];
+    NSError *error = nil;
+    if ([session overrideOutputAudioPort:override error:&error]) {
+      _portOverride = override;
+    } else {
+      RTCLogError(@"Error overriding output port: %@",
+                  error.localizedDescription);
+    }
+    [session unlockForConfiguration];
+  }];
+}
+
 - (void)videoCallViewDidEnableStats:(ARDVideoCallView *)view {
   _client.shouldGetStats = YES;
   _videoCallView.statsView.hidden = NO;
 }
 
 #pragma mark - Private
 
 - (void)setLocalVideoTrack:(RTCVideoTrack *)localVideoTrack {
   if (_localVideoTrack == localVideoTrack) {
     return;
@@ skipping 57 matching lines @@
 - (void)showAlertWithMessage:(NSString*)message {
   UIAlertView* alertView = [[UIAlertView alloc] initWithTitle:nil
                                                       message:message
                                                      delegate:nil
                                             cancelButtonTitle:@"OK"
                                             otherButtonTitles:nil];
   [alertView show];
 }
 
 @end