Why is it not possible to use the MPMoviePlayerController more than once?

Question

In MonoTouch, we ran into this problem with the Movie Player sample in that it would only play the video once, but would not play it a second time.

I am asking this question to post an answer, since it has been hitting various folks.

Answer 1

MPMoviePlayerController is a singleton underneath the hood. If you have not properly release'd (ObjC) or Dispose()'d (MonoTouch) and you create a second instance, it will either not play, or play audio only.

Additionally if you subscribe to MPMoviePlayerScalingModeDidChangeNotification or MPMoviePlayerPlaybackDidFinishNotification or MPMoviePlayerContentPreloadDidFinishNotification, be warned that the posted NSNotification takes a reference to the MPMoviePlayerController as well, so if you keep it around, you will have a reference the player.

Although Mono's Garbage Collector will eventually kick-in, this is a case where deterministic termination is wanted (you want the reference gone now, not gone when the GC decides to perform a collection).

This is why you want to call the Dispose () method on the controller, and the Dispose() method on the notification.

For example:

// Deterministic termination, do not wait for the GC
if (moviePlayer != null){
    moviePlayer.Dispose ()
    moviePlayer = null;
}

If you were listening to notifications, call Dispose in your notification handler at the end, to release the reference that it keeps to your MPMoviePlayerController for example:

var center = NSNotificationCenter.DefaultCenter;
center.AddObserver (
    "MPMoviePlayerPlaybackDidFinishNotification"),
    (notify) => { Console.WriteLine ("Done!"); notify.Dispose (); });

Answer 2

Can't see your code Nir and I don't have edit privileges so here it is again:

The secret lays in the endPlay with setting the: moviePlayer.initialPlaybackTime = -1; before releasing it. Try it out : :)

-(void)playMovie:(NSString *)urlString{ movieURL = [NSURL URLWithString:urlString];          
moviePlayer = [[MPMoviePlayerController alloc] initWithContentURL:movieURL];    
moviePlayer.initialPlaybackTime = 0; 
//Register to receive a notification when the movie has finished playing. 
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(endPlay:) name:MPMoviePlayerPlaybackDidFinishNotification object:moviePlayer];

moviePlayer.scalingMode = MPMovieScalingModeAspectFit; 
moviePlayer.movieControlMode = MPMovieControlModeDefault;
moviePlayer.backgroundColor = [UIColor blackColor];

[moviePlayer play];

}

-(void)endPlay: (NSNotification*)notification{
 [[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerPlaybackDidFinishNotification object:moviePlayer]; 
moviePlayer.initialPlaybackTime = -1; 
[moviePlayer stop]; 
[moviePlayer release]; 
} 

Answer 3

The secret lays in the endPlay with setting the: moviePlayer.initialPlaybackTime = -1; before releasing it. Try it out : :)

-(void)playMovie:(NSString *)urlString{
    movieURL = [NSURL URLWithString:urlString]; 
    moviePlayer = [[MPMoviePlayerController alloc] initWithContentURL:movieURL];
    moviePlayer.initialPlaybackTime = 0;
    //Register to receive a notification when the movie has finished playing. 
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(endPlay:) 
                                                 name:MPMoviePlayerPlaybackDidFinishNotification 
                                               object:moviePlayer];

    moviePlayer.scalingMode = MPMovieScalingModeAspectFit; 
    moviePlayer.movieControlMode = MPMovieControlModeDefault;
    moviePlayer.backgroundColor = [UIColor blackColor];

    [moviePlayer play];

}

-(void)endPlay: (NSNotification*)notification{
    [[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerPlaybackDidFinishNotification object:moviePlayer];
    moviePlayer.initialPlaybackTime = -1;
    [moviePlayer stop];
    [moviePlayer release];
}