无缘无故调用的 AudioSessionAddPropertyListener 回调函数

Question

为了保持关注，在我的iPhone应用程序中可能插入或拔出耳机并做出适当的反应;我在我的一些类中使用以下类型的代码：

- (void)viewDidLoad
{
    [super viewDidLoad];
    …..
    routeChangeID=kAudioSessionProperty_AudioRouteChange;
    AudioSessionAddPropertyListener(routeChangeID,rvcHandleRouteChange,(__bridge void *)(self));
}
…….
void rvcHandleRouteChange(void *inUserData,AudioSessionPropertyID inPropertyID,
                          UInt32 inPropertyValueSize,const void *inPropertyValue)
{
    NSLog(@"Hi rvcHandleRouteChange has been called.");
    if (inPropertyID!=kAudioSessionProperty_AudioRouteChange) NSLog(@"WRONG CALL!!!");
    // Do some useful work ….
}

这似乎工作得很好，除了在一种情况下，rvcHandleRouteChange 回调函数被调用而没有明显的原因。即使有过滤错误呼叫的测试，它们似乎都不是"错误的呼叫"。我的意思是，在没有我插入或拔下任何耳机的情况下，它就会被调用。结果，这给我带来了很多麻烦。

有人知道为什么会发生这种情况吗？

Answer 1

1：路由更改调用甚至可以发生两次。例如，如果您插入耳机（相同的路由更改原因代码）。

2：将音频会话设置为活动状态后，将调用路由更改。这意味着至少一次。

也许您正在激活/停用音频会话中实施自己的音频中断？

这是我的任何用途的路由更改侦听器（我使用播放和记录类别）[更新到 iOS7]：

#pragma mark Route change listener
// *********************************************************************************************************
// *********** Route change listener ***********************************************************************
// *********************************************************************************************************
-(void)routeChanged:(NSNotification*)notification {
    NSLog(@"]-----------------[ Audio Route Change ]--------------------[");
    AVAudioSession *session = [AVAudioSession sharedInstance];
    //AVAudioSessionRouteDescription* prevRoute = [[notification userInfo] objectForKey:AVAudioSessionRouteChangePreviousRouteKey];
    // Reason
    NSInteger reason = [[[notification userInfo] objectForKey:AVAudioSessionRouteChangeReasonKey] integerValue];
    switch (reason) {
        case AVAudioSessionRouteChangeReasonNoSuitableRouteForCategory:
            NSLog(@"] Audio Route: The route changed because no suitable route is now available for the specified category.");
            break;
        case AVAudioSessionRouteChangeReasonWakeFromSleep:
            NSLog(@"] Audio Route: The route changed when the device woke up from sleep.");
            break;
        case AVAudioSessionRouteChangeReasonOverride:
            NSLog(@"] Audio Route: The output route was overridden by the app.");
            break;
        case AVAudioSessionRouteChangeReasonCategoryChange:
            NSLog(@"] Audio Route: The category of the session object changed.");
            break;
        case AVAudioSessionRouteChangeReasonOldDeviceUnavailable:
            NSLog(@"] Audio Route: The previous audio output path is no longer available.");
            break;
        case AVAudioSessionRouteChangeReasonNewDeviceAvailable:
            NSLog(@"] Audio Route: A preferred new audio output path is now available.");
            break;
        case AVAudioSessionRouteChangeReasonUnknown:
            NSLog(@"] Audio Route: The reason for the change is unknown.");
            break;
        default:
            NSLog(@"] Audio Route: The reason for the change is very unknown.");
            break;
    }
    // Output
    AVAudioSessionPortDescription *output = [[session.currentRoute.outputs count]?session.currentRoute.outputs:nil objectAtIndex:0];
    if ([output.portType isEqualToString:AVAudioSessionPortLineOut]) {
        NSLog(@"] Audio Route: Output Port: LineOut");
    }
    else if ([output.portType isEqualToString:AVAudioSessionPortHeadphones]) {
        NSLog(@"] Audio Route: Output Port: Headphones");
    }
    else if ([output.portType isEqualToString:AVAudioSessionPortBluetoothA2DP]) {
        NSLog(@"] Audio Route: Output Port: BluetoothA2DP");
    }
    else if ([output.portType isEqualToString:AVAudioSessionPortBuiltInReceiver]) {
        NSLog(@"] Audio Route: Output Port: BuiltInReceiver");
    }
    else if ([output.portType isEqualToString:AVAudioSessionPortBuiltInSpeaker]) {
        NSLog(@"] Audio Route: Output Port: BuiltInSpeaker");
    }
    else if ([output.portType isEqualToString:AVAudioSessionPortHDMI]) {
        NSLog(@"] Audio Route: Output Port: HDMI");
    }
    else if ([output.portType isEqualToString:AVAudioSessionPortAirPlay]) {
        NSLog(@"] Audio Route: Output Port: AirPlay");
    }
    else if ([output.portType isEqualToString:AVAudioSessionPortBluetoothLE]) {
        NSLog(@"] Audio Route: Output Port: BluetoothLE");
    }
    else {
        NSLog(@"] Audio Route: Output Port: Unknown: %@",output.portType);
    }
    // Input
    AVAudioSessionPortDescription *input = [[session.currentRoute.inputs count] ? session.currentRoute.inputs:nil objectAtIndex:0];
    if ([input.portType isEqualToString:AVAudioSessionPortLineIn]) {
        NSLog(@"] Audio Route: Input Port: LineIn");
    }
    else if ([input.portType isEqualToString:AVAudioSessionPortBuiltInMic]) {
        NSLog(@"] Audio Route: Input Port: BuiltInMic");
    }
    else if ([input.portType isEqualToString:AVAudioSessionPortHeadsetMic]) {
        NSLog(@"] Audio Route: Input Port: HeadsetMic");
    }
    else if ([input.portType isEqualToString:AVAudioSessionPortBluetoothHFP]) {
        NSLog(@"] Audio Route: Input Port: BluetoothHFP");
    }
    else if ([input.portType isEqualToString:AVAudioSessionPortUSBAudio]) {
        NSLog(@"] Audio Route: Input Port: USBAudio");
    }
    else if ([input.portType isEqualToString:AVAudioSessionPortCarAudio]) {
        NSLog(@"] Audio Route: Input Port: CarAudio");
    }
    else {
        NSLog(@"] Audio Input Port: Unknown: %@",input.portType);
    }
    NSLog(@"]--------------------------[  ]-----------------------------[");
}

请记住添加观察者，因为音频会话的委托也被弃用：

[[NSNotificationCenter defaultCenter] addObserver: self
                                                 selector: @selector(audioInterruption:)
                                                     name: AVAudioSessionInterruptionNotification
                                                   object: nil];