问MPMoviePlayerViewController内存问题

EN

    MPMoviePlayerViewController * videoPlayer = [[MPMoviePlayerViewController alloc] initWithContentURL:articleUrl];
    [videoPlayer moviePlayer].movieSourceType = MPMovieSourceTypeFile;
    [videoPlayer moviePlayer].controlStyle = MPMovieControlStyleDefault;
    [videoPlayer moviePlayer].scalingMode = MPMovieScalingModeAspectFit;
    [videoPlayer moviePlayer].fullscreen = NO;

    self.playerViewController = videoPlayer;
    [videoPlayer release];
    videoPlayer = nil;

    [[NSNotificationCenter defaultCenter] addObserver:self 
                                             selector:@selector(movieFinishedCallback:) 
                                                 name:MPMoviePlayerPlaybackDidFinishNotification 
                                               object:[playerViewController moviePlayer]];

    MPMoviePlayerController *player = [playerViewController moviePlayer];

    CGRect playerFrame = CGRectMake(20, 20, self.view.frame.size.width - 40, self.view.frame.size.height - 40); 
    player.view.frame = playerFrame;
    [self.view addSubview:player.view];
    [player play];

    - (void) movieFinishedCallback:(NSNotification*) aNotification {
    MPMoviePlayerController *player = [aNotification object];
    [[NSNotificationCenter defaultCenter] removeObserver:self 
                                                    name:MPMoviePlayerPlaybackDidFinishNotification 
                                                  object:player];
    [player.view removeFromSuperview];
    [player release];
    player = nil;

}