音频播放中断处理

这里所讲的中断处理分为两种，第一种是软件级中断，比如来电。另一种是硬件级中断，比如插入耳机。当然这个软件级和硬件级仅仅做区分解释

软件级

当出现中断时，iOS SDK会发出对应的中断通知，开发者只需要监听对应的通知完成相应操作即可。

NSNotificationCenter *nsnc = [NSNotificationCenter defaultCenter];
[nsnc addObserver:self selector:@selector(handleInterruptionChange:) name:AVAudioSessionInterruptionNotification object:[AVAudioSession sharedInstance]];


- (void)handleInterruptionChange:(NSNotification *)notification
{
    NSDictionary *info = notification.userInfo;

    AVAudioSessionInterruptionType type = [info[AVAudioSessionInterruptionTypeKey] unsignedIntegerValue];

    if (type == AVAudioSessionInterruptionTypeBegan) {
        //do something
    }
    else
    {
        AVAudioSessionInterruptionOptions options = [info[AVAudioSessionInterruptionOptionKey] unsignedIntegerValue];
        if (options == AVAudioSessionInterruptionOptionShouldResume) {
            //do something
        }
    }
}

硬件级

同理，出现硬件级中断时，AVAudioSession同样会给出对应的中断通知。这里需要注意的是耳机断开这个事件，对应的原因是AVAudioSessionRouteChangeReasonOldDeviceUnavailable

NSNotificationCenter *nsnc = [NSNotificationCenter defaultCenter];
[nsnc addObserver:self selector:@selector(handleRouteChange:) name:AVAudioSessionRouteChangeNotification object:[AVAudioSession sharedInstance]];

- (void)handleRouteChange:(NSNotification *)notification {

    NSDictionary *info = notification.userInfo;

    AVAudioSessionRouteChangeReason reason = [info[AVAudioSessionRouteChangeReasonKey] unsignedIntValue];

    if (reason == AVAudioSessionRouteChangeReasonOldDeviceUnavailable) 
    {
        AVAudioSessionRouteDescription *previousRoute = info[AVAudioSessionRouteChangePreviousRouteKey];

        AVAudioSessionPortDescription *previousOutput = previousRoute.outputs[0];
        NSString *portType = previousOutput.portType;

        if ([portType isEqualToString:AVAudioSessionPortHeadphones]) 
        {
            //do something...
        }
    }
}