objective-c - Objective C Play ビデオ

Question

ここに私の実装ファイルがあります:

-(IBAction)playvideo {

NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle]
                                     pathForResource:@"Intro" ofType:@"mp4"]];

MPMoviePlayerViewController *playercontroller = [[MPMoviePlayerViewController alloc] 
                                                 initWithContentURL:url];

[self presentMoviePlayerViewControllerAnimated:playercontroller];

playercontroller.moviePlayer.movieSourceType = MPMovieSourceTypeFile;

[playercontroller.moviePlayer play];

playercontroller = nil;


} 

そして、ここに奇妙なエラーがあります：

2012-08-03 01:48:40.085 Assaultive[5569:16a03] An instance 0x9b5ad50 of class AVPlayerItem was deallocated while key value observers were still registered with it. Observation info was leaked, and may even become mistakenly attached to some other object. Set a breakpoint on NSKVODeallocateBreak to stop here in the debugger. Here's the current observation info:
<NSKeyValueObservationInfo 0x8549f10> (
<NSKeyValueObservance 0x9b5cde0: Observer: 0x9b58690, Key path: nonForcedSubtitleDisplayEnabled, Options: <New: YES, Old: NO, Prior: NO> Context: 0x0, Property: 0x9b5ce60>
<NSKeyValueObservance 0x9b5cfa0: Observer: 0x9b54b90, Key path: presentationSize, Options: <New: NO, Old: NO, Prior: NO> Context: 0x0, Property: 0x9957780>
)

プレーヤー ビューをロードし、サブプレーヤー ビューを直接閉じます。

助言がありますか？