avplayer在播放视频时，如何检测网速不好时的卡顿状态？

NSURL *playUrl=[NSURL URLWithString:url];
AVURLAsset *asset=[AVURLAsset assetWithURL:playUrl];


[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"]
                     completionHandler:^{

    AVKeyValueStatus status=[asset statusOfValueForKey:@"tracks" error:nil];

     NSLog(@"status==%d",status);
    if (status==AVKeyValueStatusLoaded) {




        [[NSNotificationCenter defaultCenter]removeObserver:self
                                                       name:UIApplicationDidEnterBackgroundNotification object:nil];


        [[NSNotificationCenter defaultCenter]addObserver:self
                                                selector:@selector(stopPlay)
                                                    name:UIApplicationDidEnterBackgroundNotification
                                                  object:nil];

       items=[AVPlayerItem playerItemWithAsset:asset];
        if (_player) {
            RELEASE_SAFELY(_player);
        }
        _player=[[AVPlayer alloc]initWithPlayerItem:items];


        [_playerView setPlayer:_player];
        [_player play];

以上方法无法处理由于网络原因造成的中断，卡顿现象。求解决方案。

http://stackoverflow.com/questions/6880817/ios-avplayer-trigger-streaming-is-out-of-buffer