如何使用 AVFoundation 加载多个本地文件

Question

我希望使用 AVFoundation 加载和播放电影文件。我遇到的第一个问题是尝试加载多个本地文件。我找到的代码只允许我加载一个。如果我调用下面的方法，它将退出并出现异常：

由于未捕获的异常“NSRangeException”而终止应用程序，原因：“无法删除关键路径“currentItem.nonForcedSubtitleDisplayEnabled”的观察者，因为它未注册为观察者。”

感谢您的任何建议

- (IBAction)loadAssetFromFile:(NSString*)fileName withExtension:(NSString*)extension {

NSURL *fileURL = [[NSBundle mainBundle]
                  URLForResource:fileName withExtension:extension];

AVURLAsset *asset = [AVURLAsset URLAssetWithURL:fileURL options:nil];
NSString *tracksKey = @"tracks";

[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:tracksKey] completionHandler:
 ^{

     // Completion handler block.
     NSError *error = nil;
     AVKeyValueStatus status = [asset statusOfValueForKey:tracksKey error:&error];

     if (status == AVKeyValueStatusLoaded) {

         self.playerItem = [AVPlayerItem playerItemWithAsset:asset];

         [playerItem addObserver:self forKeyPath:@"status" options:0 context:&ItemStatusContext];

         [[NSNotificationCenter defaultCenter] addObserver:self
                                                  selector:@selector(playerItemDidReachEnd:)
                                                      name:AVPlayerItemDidPlayToEndTimeNotification
                                                    object:playerItem];
         self.player = [AVPlayer playerWithPlayerItem:playerItem];
         [playerView setPlayer:player];
     }
     else {
         // Deal with the error appropriately.
         NSLog(@"The asset's tracks were not loaded:\n%@", [error localizedDescription]);
     }

 }];

}

Answer 1

哎呀，我自己想出来了，看看我对这个问题的回答：MPMoviePlayerController切换电影导致白色闪光