无法在iOS5中使用AVQueuePlayer播放背景音乐

问题描述：

我试图构建应用程序播放本地音乐，但不幸的是，我无法使用AVQueuePlayer在iOS5中进行背景音频播放。无法在iOS5中使用AVQueuePlayer播放背景音乐

在我viewDidLoad中，我得到这个代码：

// Player setup 
mAudioPlayer = [[AVQueuePlayer alloc] init]; 
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(playerItemDidReachEnd:) name:AVPlayerItemDidPlayToEndTimeNotification object:nil]; 
[mAudioPlayer addPeriodicTimeObserverForInterval:CMTimeMakeWithSeconds(1.0, 1) queue:NULL usingBlock:^(CMTime time) { 
    [self updatePositionOnDisplay]; 
}]; 

// Audio session setup 
NSError *setCategoryErr = nil; 
NSError *activationErr = nil; 
[[AVAudioSession sharedInstance] setCategory: AVAudioSessionCategoryPlayback error: &setCategoryErr]; 
[[AVAudioSession sharedInstance] setActive: YES error: &activationErr];

这里是我的 “playerItemDidReachEnd” 的方法：

- (void)playerItemDidReachEnd:(NSNotification*)notification 
{ 
    NSLog(@"playerItemDidReachEnd"); 

    UIBackgroundTaskIdentifier newTaskID = [[UIApplication sharedApplication] beginBackgroundTaskWithExpirationHandler:^{ 
     [[UIApplication sharedApplication] endBackgroundTask:newTaskID]; 
    }]; 
    NSLog(@"playerItemDidReachEnd 2"); 

    NSLog(@"searching next song"); 
    mCurrentSong = [self getNextSongWithIsSwitched:NO]; 
    if(mCurrentSong != nil){ 
     NSLog(@"Start : %@ - %@", mCurrentSong.artist, mCurrentSong.title); 

     mTapeTitle.text = [NSString stringWithFormat:@"%@ - %@", mCurrentSong.artist, mCurrentSong.title]; 

     AVPlayerItem* i = [[AVPlayerItem alloc] initWithURL:[NSURL URLWithString:mCurrentSong.path]]; 

     if(i != nil){ 
      [mAudioPlayer insertItem:i afterItem:nil]; 
     }else 
      NSLog(@"BING!! no AVPlayerItem created for song's path: %@", mCurrentSong.path); 

     [i release]; 
    }else{ 
     NSLog(@"no song found"); 
     [mAudioPlayer pause]; 
     isPlaying = NO;   
     [mPlayButton setSelected:NO]; 
    } 

    [[UIApplication sharedApplication] endBackgroundTask:newTaskID]; 
    newTaskID = UIBackgroundTaskInvalid; 
}

当我开始播放，它的工作原理，并保持当我切换播放关闭屏幕。但是，当歌曲结束后，这里的日志

2012-03-01 10:00:27.342 DEMO[3096:707] playerItemDidReachEnd 
2012-03-01 10:00:27.360 DEMO[3096:707] playerItemDidReachEnd 2 
2012-03-01 10:00:27.363 DEMO[3096:707] searching next song 
2012-03-01 10:00:27.381 DEMO[3096:707] Start : Moby - Ah-Ah

但没有歌曲有效启动...

谁能告诉我什么是错我的代码？

非常感谢。

答

试评下一行

[[UIApplication sharedApplication] endBackgroundTask:newTaskID]; 
newTaskID = UIBackgroundTaskInvalid;

，如果它工作，那么你需要一个观察者添加到mAudioPlayer为“currentItem.status”时，状态AVPlayerStatusReadyToPlay然后结束后台任务

无法在iOS5中使用AVQueuePlayer播放背景音乐

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