objective-c - AVPlayer無法播放本機影片文件
如題，AVPlayer這貨整死不播放本地視頻文件(視頻絕對沒問題)，而網絡加載鏈接是可以播放的，煩勞各位大大看看咋回事？
程式碼如下：
NSURL *url = [NSURL fileURLWithPath:@"/Users/tangkunyin/Desktop/mp4ForDownloadTest.mp4"];
AVAsset *movieAsset = [AVURLAsset assetWithURL:url];
AVPlayerItem *playerItem = [AVPlayerItem playerItemWithAsset:movieAsset];
AVPlayer *player = [AVPlayer playerWithPlayerItem:playerItem];
AVPlayerLayer *playerLayer = [AVPlayerLayer playerLayerWithPlayer:player];
playerLayer.frame = CGRectMake(0, 0, KDeviceWidth, 300);
playerLayer.videoGravity=AVLayerVideoGravityResize;
[self.view.layer addSublayer:playerLayer];
[player play];