iOS-关于AVAudioSession的使用——后台播放音乐

+ (UIBackgroundTaskIdentifier)backgroundPlayerID:(UIBackgroundTaskIdentifier)backTaskId{    // 1. 设置并激活音频会话类别       AVAudioSession *session = [AVAudioSession sharedInstance];    [session AVAudioSessionCategoryPlayback error:nil];    [session setActive:YES error:nil];    // 2. 允许应用程序接收远程控制    [[UIapplication sharedApplication] beginReceivingRemoteControlEvents];    // 3. 设置后台任务ID      UIBackgroundTaskIdentifier newTaskId = UIBackgroundTaskInvalid;    newTaskId = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:nil];    if (newTaskId != UIBackgroundTaskInvalid && backTaskId != UIBackgroundTaskInvalid) {        [[UIApplication sharedApplication] endBackgroundTask:backTaskId];    }    return newTaskId;}

//后台播放音频设置  AVAudioSession *session = [AVAudioSession sharedInstance];    [session setActive:YES error:nil];    [session setCategory:AVAudioSessionCategoryPlayback error:nil];     //让app支持接受远程控制事件  [[UIApplication sharedApplication] beginReceivingRemoteControlEvents];  

// 后台播放任务IdUIBackgroundTaskIdentifier  _bgTaskId;// 设置音频会话，允许后台播放_bgTaskId = [SoundTool backgroundPlayerID:_bgTaskId];