AudioSessionAddPropertyListener回調函數無緣無故被調用

Question

為了留意我的iPhone應用程序中可能插入或拔出的耳機，並做出適當的反應； 我在幾個類中使用以下類型的代碼：

- (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 ….
}

這似乎工作得很好，除了在沒有明顯原因的情況下調用rvcHandleRouteChange回調函數的情況下。 即使進行了篩選錯誤呼叫的測試，也似乎沒有一個是“錯誤呼叫”。 我的意思是沒有我就可以插拔任何耳機。 結果，這給我帶來很多麻煩。

任何人都知道為什么會發生這種情況嗎？

Answer 1

1：路由更改呼叫甚至可以發生兩次。 例如，如果您插入耳機（相同的路線更改原因碼）。

2：將音頻會話設置為活動后，RouteChange會被調用。 這意味着至少一次。

也許您在激活/停用音頻會話時實現了自己的音頻中斷？

這是我的路線更改偵聽器，可用於任何用途（我使用playAndRecord類別）[更新為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(@"]--------------------------[  ]-----------------------------[");

}

切記添加觀察者，因為音頻會話的委托也已棄用：

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