AVPlayer无法从音乐库播放

Question

我正在尝试使用AVPlayer从我的iPhone音乐库播放一首歌.一切似乎都准备好了,但玩家根本不会发出任何声音.我一直在努力解决这个问题,任何帮助都将不胜感激!

注意:我意识到我可以使用AVAudioPlayer,但我想直接从我的音乐库中读取文件,据我所知,AVAudioPlayer不支持(我必须首先导出歌曲,占用更多时间).我无法使用MPMusicPlayerController,因为最终目标是将歌曲转换为NSData并在另一台设备上播放.

最重要的是,我想知道为什么这段代码没有播放:

NSArray *itemsFromQuery = [[MPMediaQuery songsQuery] items];
MPMediaItem *song = [itemsFromQuery objectAtIndex:29];
NSURL *songURL = [song valueForProperty:MPMediaItemPropertyAssetURL];
AVURLAsset *urlAsset = [[AVURLAsset alloc] initWithURL:songURL options:nil];

NSArray *keyArray = [[NSArray alloc] initWithObjects:@"tracks", nil];

[urlAsset loadValuesAsynchronouslyForKeys:keyArray completionHandler:^{

    AVPlayerItem *playerItem = [[AVPlayerItem alloc] initWithAsset:urlAsset];

    AVPlayer *player = [[AVPlayer alloc] initWithPlayerItem:playerItem];

    while (true) {
        if (player.status == AVPlayerStatusReadyToPlay && playerItem.status == AVPlayerItemStatusReadyToPlay) {
            break;
        }
    }

    if (player.status == AVPlayerStatusReadyToPlay && playerItem.status == AVPlayerItemStatusReadyToPlay) {
        NSLog(@"Ready to play");
        [player play];
    }
    else 
        NSLog(@"Not ready to play");
}];

在调用play方法后,输出为"Ready to play",AVPlayer的"rate"属性为1.0.MPMediaItem存在,我可以使用valueForProperty方法来获得正确的标题,艺术家等.任何想法为什么没有声音来自播放器？

Answer 1

发现有用的东西:

1. 我把AVPlayer作为财产(感谢小费meggar!)

2. 在使用initWithAsset方法之前,我确保AVPlayer为零.

   NSArray *itemsFromQuery = [[MPMediaQuery songsQuery] items];
   MPMediaItem *song = [itemsFromQuery objectAtIndex:0];
   NSURL *songURL = [song valueForProperty:MPMediaItemPropertyAssetURL];
   AVURLAsset *urlAsset = [[AVURLAsset alloc] initWithURL:songURL options:nil];
   
   NSArray *keyArray = [[NSArray alloc] initWithObjects:@"tracks", nil];
   
   [urlAsset loadValuesAsynchronouslyForKeys:keyArray completionHandler:^{
   
       AVPlayerItem *playerItem = [[AVPlayerItem alloc] initWithAsset:urlAsset];
   
       player = nil;
       player = [[AVPlayer alloc] initWithPlayerItem:playerItem];
   
       while (true) {
           if (player.status == AVPlayerStatusReadyToPlay && playerItem.status == AVPlayerItemStatusReadyToPlay)
               break;
       }
   
       [player play];
   
   }];
   

希望这可以帮助别人!