Add logging around audio session interruptions

webrtc/modules/audio_device/ios/objc/RTCAudioSession.mm

 /*
  *  Copyright 2016 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.
  */
 
@@ skipping 68 matching lines @@
     // hint to enable or disable audio that is secondary.
     [center addObserver:self
                selector:@selector(handleSilenceSecondaryAudioHintNotification:)
                    name:AVAudioSessionSilenceSecondaryAudioHintNotification
                  object:nil];
     // Also track foreground event in order to deal with interruption ended situation.
     [center addObserver:self
                selector:@selector(handleApplicationDidBecomeActive:)
                    name:UIApplicationDidBecomeActiveNotification
                  object:nil];
+    RTCLog(@"RTCAudioSession init: (%p)", self);

[tkchin_webrtc, 2017/03/29 20:02:51]

nit: "RTCAudioSession (%p): init"
(usually ptr value is shown first)

[Chuck, 2017/03/29 20:29:18]

Done.

   }
   return self;
 }
 
 - (void)dealloc {
   [[NSNotificationCenter defaultCenter] removeObserver:self];
+  RTCLog(@"RTCAudioSession dealloc: (%p)", self);
 }
 
 - (NSString *)description {
   NSString *format =
       @"RTCAudioSession: {\n"
        "  category: %@\n"
        "  categoryOptions: %ld\n"
        "  mode: %@\n"
        "  isActive: %d\n"
        "  sampleRate: %.2f\n"
@@ skipping 55 matching lines @@
 }
 
 - (BOOL)isAudioEnabled {
   @synchronized(self) {
     return _isAudioEnabled;
   }
 }
 
 // TODO(tkchin): Check for duplicates.
 - (void)addDelegate:(id<RTCAudioSessionDelegate>)delegate {
+  RTCLog(@"Adding delegate: (%p)", delegate);
   if (!delegate) {
     return;
   }
   @synchronized(self) {
     _delegates.push_back(delegate);
     [self removeZeroedDelegates];
   }
 }
 
 - (void)removeDelegate:(id<RTCAudioSessionDelegate>)delegate {
+  RTCLog(@"Removing delegate: (%p)", delegate);
   if (!delegate) {
     return;
   }
   @synchronized(self) {
     _delegates.erase(std::remove(_delegates.begin(),
                                  _delegates.end(),
                                  delegate),
                      _delegates.end());
     [self removeZeroedDelegates];
   }
@@ skipping 348 matching lines @@
       RTCLog(@"Another application's primary audio has stopped.");
       break;
   }
 }
 
 - (void)handleApplicationDidBecomeActive:(NSNotification *)notification {
   if (self.isInterrupted) {
     RTCLog(@"Application became active after an interruption. Treating as interruption end.");
     self.isInterrupted = NO;
     [self updateAudioSessionAfterEvent];
-    [self notifyDidEndInterruptionWithShouldResumeSession:YES];
   }
+  // Always treat application becoming active as an interruption end event.
+  [self notifyDidEndInterruptionWithShouldResumeSession:YES];

[tkchin_webrtc, 2017/03/29 20:02:51]

Hm. I don't recall the details here - but can you check that the audio device
doesn't freak out (ie doesn't try to reinit itself during a call) if we do this
each time app comes to foreground?

Also, can we add a way to distinguish between interruption ends that occur as a
result of app foregrounding, as opposed to when we're notified by OS? Right now
this one appears to be silent.

[Chuck, 2017/03/29 20:29:18]

Modified the logging here so it always logs something.

It looks like this handles multiple end interrupts calls well. It checks the
state of the audio unit and only starts it if needed.

 }
 
 #pragma mark - Private
 
 + (NSError *)lockError {
   NSDictionary *userInfo = @{
     NSLocalizedDescriptionKey:
         @"Must call lockForConfiguration before calling this method."
   };
   NSError *error =
@@ skipping 287 matching lines @@
 - (void)notifyDidStopPlayOrRecord {
   for (auto delegate : self.delegates) {
     SEL sel = @selector(audioSessionDidStopPlayOrRecord:);
     if ([delegate respondsToSelector:sel]) {
       [delegate audioSessionDidStopPlayOrRecord:self];
     }
   }
 }
 
 @end