Treat foreground event as interruption end.

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.
  */
 
 #import "webrtc/modules/audio_device/ios/objc/RTCAudioSession.h"
 
+#import <UIKit/UIKit.h>
+
 #include "webrtc/base/atomicops.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/modules/audio_device/ios/audio_device_ios.h"
 
 #import "WebRTC/RTCLogging.h"
 #import "webrtc/modules/audio_device/ios/objc/RTCAudioSession+Private.h"
 #import "webrtc/modules/audio_device/ios/objc/RTCAudioSessionConfiguration.h"
 
 NSString * const kRTCAudioSessionErrorDomain = @"org.webrtc.RTCAudioSession";
 NSInteger const kRTCAudioSessionErrorLockRequired = -1;
 NSInteger const kRTCAudioSessionErrorConfiguration = -2;
 
 // This class needs to be thread-safe because it is accessed from many threads.
 // TODO(tkchin): Consider more granular locking. We're not expecting a lot of
 // lock contention so coarse locks should be fine for now.
 @implementation RTCAudioSession {
   rtc::CriticalSection _crit;
   AVAudioSession *_session;
   volatile int _activationCount;
   volatile int _lockRecursionCount;
   volatile int _webRTCSessionCount;
   BOOL _isActive;
   BOOL _useManualAudio;
   BOOL _isAudioEnabled;
   BOOL _canPlayOrRecord;
+  BOOL _isInterrupted;
 }
 
 @synthesize session = _session;
 @synthesize delegates = _delegates;
 
 + (instancetype)sharedInstance {
   static dispatch_once_t onceToken;
   static RTCAudioSession *sharedInstance = nil;
   dispatch_once(&onceToken, ^{
     sharedInstance = [[self alloc] init];
@@ skipping 16 matching lines @@
                  object:nil];
     // TODO(tkchin): Maybe listen to SilenceSecondaryAudioHintNotification.
     [center addObserver:self
                selector:@selector(handleMediaServicesWereLost:)
                    name:AVAudioSessionMediaServicesWereLostNotification
                  object:nil];
     [center addObserver:self
                selector:@selector(handleMediaServicesWereReset:)
                    name:AVAudioSessionMediaServicesWereResetNotification
                  object:nil];
+    // Also track foreground event in order to deal with interruption ended situation.
+    [center addObserver:self
+               selector:@selector(handleApplicationDidBecomeActive:)
+                   name:UIApplicationDidBecomeActiveNotification
+                 object:nil];
   }
   return self;
 }
 
 - (void)dealloc {
   [[NSNotificationCenter defaultCenter] removeObserver:self];
 }
 
 - (NSString *)description {
   NSString *format =
@@ skipping 342 matching lines @@
 
 - (void)handleInterruptionNotification:(NSNotification *)notification {
   NSNumber* typeNumber =
       notification.userInfo[AVAudioSessionInterruptionTypeKey];
   AVAudioSessionInterruptionType type =
       (AVAudioSessionInterruptionType)typeNumber.unsignedIntegerValue;
   switch (type) {
     case AVAudioSessionInterruptionTypeBegan:
       RTCLog(@"Audio session interruption began.");
       self.isActive = NO;
+      self.isInterrupted = YES;
       [self notifyDidBeginInterruption];
       break;
     case AVAudioSessionInterruptionTypeEnded: {
       RTCLog(@"Audio session interruption ended.");
+      self.isInterrupted = NO;
       [self updateAudioSessionAfterEvent];
       NSNumber *optionsNumber =
           notification.userInfo[AVAudioSessionInterruptionOptionKey];
       AVAudioSessionInterruptionOptions options =
           optionsNumber.unsignedIntegerValue;
       BOOL shouldResume =
           options & AVAudioSessionInterruptionOptionShouldResume;
       [self notifyDidEndInterruptionWithShouldResumeSession:shouldResume];
       break;
     }
@@ skipping 47 matching lines @@
   [self updateAudioSessionAfterEvent];
   [self notifyMediaServicesWereLost];
 }
 
 - (void)handleMediaServicesWereReset:(NSNotification *)notification {
   RTCLog(@"Media services were reset.");
   [self updateAudioSessionAfterEvent];
   [self notifyMediaServicesWereReset];
 }
 
+- (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];
+  }
+}
+
 #pragma mark - Private
 
 + (NSError *)lockError {
   NSDictionary *userInfo = @{
     NSLocalizedDescriptionKey:
         @"Must call lockForConfiguration before calling this method."
   };
   NSError *error =
       [[NSError alloc] initWithDomain:kRTCAudioSessionErrorDomain
                                  code:kRTCAudioSessionErrorLockRequired
@@ skipping 40 matching lines @@
 }
 
 - (int)webRTCSessionCount {
   return _webRTCSessionCount;
 }
 
 - (BOOL)canPlayOrRecord {
   return !self.useManualAudio || self.isAudioEnabled;
 }
 
+- (BOOL)isInterrupted {
+  @synchronized(self) {
+    return _isInterrupted;
+  }
+}
+
+- (void)setIsInterrupted:(BOOL)isInterrupted {
+  @synchronized(self) {
+    if (_isInterrupted == isInterrupted) {
+      return;
+   }
+   _isInterrupted = isInterrupted;
+  }
+}
+
 - (BOOL)checkLock:(NSError **)outError {
   // Check ivar instead of trying to acquire lock so that we won't accidentally
   // acquire lock if it hasn't already been called.
   if (!self.isLocked) {
     if (outError) {
       *outError = [RTCAudioSession lockError];
     }
     return NO;
   }
   return YES;
@@ skipping 210 matching lines @@
 - (void)notifyDidStopPlayOrRecord {
   for (auto delegate : self.delegates) {
     SEL sel = @selector(audioSessionDidStopPlayOrRecord:);
     if ([delegate respondsToSelector:sel]) {
       [delegate audioSessionDidStopPlayOrRecord:self];
     }
   }
 }
 
 @end