MPMoviePlayerController prepareToPlay not working with HTTP Live Streaming

I'm trying to play an HTTP live streaming video using a MPMoviePlayerController object, inside a modal view controller. If I run the code like this, everything works fine. I get a MPMoviePlaybackStatePlaying notification, and the video plays.

- (void)viewDidLoad {
    [super viewDidLoad];

    [[NSNotificationCenter defaultCenter] addObserver:self  selector:@selector(moviePlayerPlaybackStateDidChange:)  name:MPMoviePlayerPlaybackStateDidChangeNo开发者_运维问答tification  object:nil];

    NSURL *url = [NSURL URLWithString:@"http://devimages.apple.com/iphone/samples/bipbop/bipbopall.m3u8"];
    self.moviePlayerController = [[[MPMoviePlayerController alloc] initWithContentURL:url] autorelease]; 
    self.moviePlayerController.view.frame = CGRectMake(0,0,320,416);
    self.moviePlayerController.controlStyle = MPMovieControlStyleNone;
    self.moviePlayerController.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
    [self.view addSubview:self.moviePlayerController.view];  
    self.moviePlayerController.fullscreen = NO;  
    [self.moviePlayerController play]; 
}

I would prefer to use the prepareToPlay method, so that I can show a loading indicator, and for a nicer experience. However, I don't seem to be able to get this working. No MPMoviePlayerPlaybackStateDidChangeNotification ever gets called, and the stream doesn't play. The activity indicator just sits there spinning forever.

I've confirmed that prepareToPlay does get called, but nothing else seems to happen after that. I've also confirmed that this code works fine with a local movie file. It just seems to be with HTTP Live Streaming which fails. Can anyone see what I'm doing wrong?

- (void)viewDidLoad {
    [super viewDidLoad];

    [self.activityIndicator startAnimating];

    [[NSNotificationCenter defaultCenter] addObserver:self  selector:@selector(moviePlayerPlaybackStateDidChange:)  name:MPMoviePlayerPlaybackStateDidChangeNotification  object:nil];

    NSURL *url = [NSURL URLWithString:@"http://devimages.apple.com/iphone/samples/bipbop/bipbopall.m3u8"];
    self.moviePlayerController = [[[MPMoviePlayerController alloc] initWithContentURL:url] autorelease]; 

    [self registerForMovieNotifications]; 
}

- (void)registerForMovieNotifications {
    //movie is ready to play notifications
    if ([self.moviePlayerController respondsToSelector:@selector(loadState)]) {
        //this is a 3.2+ device
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(moviePlayerLoadStateChanged:) name:MPMoviePlayerLoadStateDidChangeNotification object:nil];       
        self.moviePlayerController.movieSourceType = MPMovieSourceTypeStreaming;
        [self.moviePlayerController prepareToPlay];
    } else {
        //pre-3.2 device
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(moviePreloadDidFinish:) name:MPMoviePlayerContentPreloadDidFinishNotification object:nil];
    }

    //movie has finished notification
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(moviePlayBackDidFinish:) name:MPMoviePlayerPlaybackDidFinishNotification object:nil];
}

- (void) moviePlayerPlaybackStateDidChange:(NSNotification*)notification {
    NSLog(@"playbackDidChanged");
    MPMoviePlayerController *moviePlayer = notification.object;
    MPMoviePlaybackState playbackState = moviePlayer.playbackState;
    if(playbackState == MPMoviePlaybackStateStopped) {
        NSLog(@"MPMoviePlaybackStateStopped");
    } else if(playbackState == MPMoviePlaybackStatePlaying) {
        NSLog(@"MPMoviePlaybackStatePlaying");
    } else if(playbackState == MPMoviePlaybackStatePaused) {
        NSLog(@"MPMoviePlaybackStatePaused");
    } else if(playbackState == MPMoviePlaybackStateInterrupted) {
        NSLog(@"MPMoviePlaybackStateInterrupted");
    } else if(playbackState == MPMoviePlaybackStateSeekingForward) {
        NSLog(@"MPMoviePlaybackStateSeekingForward");
    } else if(playbackState == MPMoviePlaybackStateSeekingBackward) {
        NSLog(@"MPMoviePlaybackStateSeekingBackward");
    }
}

//3.2+ devices
- (void)moviePlayerLoadStateChanged:(NSNotification*)notification {
    NSLog(@"load state changed");

    //unless state is unknown, start playback
    if ([self.moviePlayerController loadState] != MPMovieLoadStateUnknown) {
        [[NSNotificationCenter defaultCenter] removeObserver:self name:MPMoviePlayerLoadStateDidChangeNotification object:nil];

        self.moviePlayerController.view.frame = CGRectMake(0,0,320,416);
        self.moviePlayerController.controlStyle = MPMovieControlStyleNone;
        self.moviePlayerController.view.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
        [self.view addSubview:self.moviePlayerController.view];  
        self.moviePlayerController.fullscreen = NO;  
        [self.moviePlayerController play]; 
    }
}

//pre 3.2 devices
- (void) moviePreloadDidFinish:(NSNotification*)notification  {
    // Remove observer
    [[NSNotificationCenter  defaultCenter] removeObserver:self name:MPMoviePlayerContentPreloadDidFinishNotification object:nil];
    [self.moviePlayerController play];
}

---

I don't know why, but I was able to solve this by moving the line self.moviePlayerController.controlStyle = MPMovieControlStyleNone; out of the moviePlayerLoadStateChanged: method, and into the viewDidLoad method.

Anyone have any ideas why this made a difference?