title: Why MPMoviePlayerController alway show empty black screen?
body: <p>Code for init video player:</p>
  
  <pre><code>NSURL * url  =[NSURL URLWithString: @"http://www.ebookfrenzy.com/ios_book/movie/movie.mov"];
  _player = [[MPMoviePlayerController alloc] initWithContentURL: url ];
  [_player.view setFrame: self.view.bounds];
  [self.view addSubview:_player.view];
  _player.scalingMode = MPMovieScalingModeAspectFit;
        //    [_player prepareToPlay];
  [_player play];
  </code></pre>
  
  <p>But it always show black screen when I test in ipad  iOS 7, how I fix it?</p>