MPMoviePlayerController does not play video content [due to ARC and memory management]

Question

I am trying to get a video playing an iOS application using MPMoviePlayerController to add a movie view to an existing view when the user clicks a button. The view looks like a black box in the correct position and that's it, but nothing happens. I expect the movie to start playing, but nothing happens and no tips from the app about why.

Can anyone see where this is happening?

-(IBAction) playButtonClicked:(id)sender { NSString* path = [[NSBundle mainBundle] pathForResource:@"sample_mpeg4" ofType:@"mp4"]; NSLog(@"Using videoPath %@", path); NSURL* url = [NSURL fileURLWithPath:path]; MPMoviePlayerController *player = [[MPMoviePlayerController alloc] initWithContentURL:url]; [self.view addSubview:player.view]; player.view.frame = CGRectMake(10, 10, 300, 220); [player play]; 

}

The movie exists and records the correct path, but the movie does not play.

 2012-07-06 11:51:13.492 experiments[84702:12203] Using videoPath /Users/marius/Library/Application Support/iPhone Simulator/5.1/Applications/9799C851-8D2B-4CFE-8CFA-A4C4C954787F/experiments.app/sample_mpeg4.mp4 

From what I read and understood, this should work. Any tips or suggestions on what to try?

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I moved the movie to an HTTP server (fg.mp4) and closed the access logs. When you click on the play button, a regular black window appears. Serverside I find two entries in the log:

 168.122.xx - - [06/Jul/2012:22:42:33 +0200] "GET /fg.mp4 HTTP/1.1" 304 192 "-" "AppleCoreMedia/1.0.0.9B176 (iPhone Simulator; U; CPU OS 5_1 like Mac OS X; en_us)" 168.122.xx - - [06/Jul/2012:22:42:33 +0200] "GET /fg.mp4 HTTP/1.1" 206 33304 "-" "AppleCoreMedia/1.0.0.9B176 (iPhone Simulator; U; CPU OS 5_1 like Mac OS X; en_us)" 

Thus, the phone receives parts of the contents of the film, and, accordingly, prepares to get peace when necessary. Is there some obvious parameter for MPMoviePlayerController that I am missing?

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UPDATE: Solution and working code

The problem is caused by ARC and the fact that after calling the method that configures the controller, the link to MPMoviePlayerController not saved. Solution: add a class variable to the class and use it to store a reference to the controller for the duration of the movie.

At the beginning of a class declaration (outside of any messages / definition functions):

 MPMoviePlayerController* mpController; 

And the abbreviation used playButtonClicked uses this variable to track the controller:

 NSString* path = [[NSBundle mainBundle] pathForResource:@"sample_mpeg4" ofType:@"mp4"]; NSURL* url = [NSURL fileURLWithPath:path]; mpController = [[MPMoviePlayerController alloc] initWithContentURL:url]; mpController.view.frame = CGRectMake(10, 10, 300, 220); [self.view addSubview:mpController.view]; [mpController play]; 

Answer 1

Like my answer to MPMoviePlayerController Playback stops before the video ends , it looks like a memory management issue (instance lifetime). Assuming you are compiling with ARC, the player variable is freed when the playButtonClicked: method playButtonClicked: . At this point, the MPMoviePlayerController instance takes its bat and ball and returns home.

Try to assign an instance of MPMoviePlayerController strong variable or instance property.

Answer 2

Nothing seems completely inappropriate to me. Here are some debugging tips to help solve the problem:

• try using the url of the mp4 file served via http --- which should tell you if this is a user interface problem or an asset problem.
• try checking the url for properties such as file length, and make sure it matches exactly what you expected.