我希望使用 AVFoundation 来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。我发现的代码只允许我加载一个。如果我调用下面的方法，它会退出并出现异常：
由于未捕获的异常“NSRangeException”而终止应用程序，原因：“无法从中删除关键路径“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]);
}
}];
}