Playing a video with Xamarin for iOS broken after latest update

问题

The following code in Xamarin for iOS was working fine prior to the Xamarin for iOS update to v2.0.50727

This is the code in a custom renderer in a Xamarin Forms app

 class WatchVideoRenderer : PageRenderer
{
    MPMoviePlayerController moviePlayer;

    protected override void OnElementChanged(VisualElementChangedEventArgs e)
    {
        base.OnElementChanged(e);

        var url =  new NSUrl("http://192.168.12.4:8085/MediaUploads/1/211/520140731170618/DPM202.mp4");
        moviePlayer = new MPMoviePlayerController();
        moviePlayer.ContentUrl = url;
        moviePlayer.View.Frame = new CGRect((float)((NativeView.Bounds.Width - 600) / 2), (float)((NativeView.Bounds.Height - 450) / 2), 600, 400);

        MPMoviePlayerController.Notifications.ObserveLoadStateDidChange(OnLoadStateChanged);
        MPMoviePlayerController.Notifications.ObservePlaybackDidFinish(OnPlaybackComplete);

        View.AddSubview(moviePlayer.View);

        moviePlayer.PrepareToPlay();
        moviePlayer.ShouldAutoplay = true;
        moviePlayer.Play();
    }

    private void OnLoadStateChanged(object sender, NSNotificationEventArgs e)
    {
        if (moviePlayer.LoadState == MPMovieLoadState.Playable)
        {

        }
    }

    private void OnPlaybackComplete(object sender, MPMoviePlayerFinishedEventArgs e)
    {

    }
}

As i said this was working till day before yesterday, after which I installed 2 updates on Xamarin. iOS & this is now failing. All i see is a black canvas & the video never loads. No notifications from the MPMoviePlayerController are ever raised. There is a release of this app scheduled for next week & this last minute bug is causing me headaches. Any help is really appreciated.

回答1:

I resolved a similar issue by pushing a new image context and that did the trick. I modified the code to include the BeginImageContext() and EndImageContext().

UIGraphics.BeginImageContext(new CGSize(1,1));
var url =  new NSUrl("http://192.168.12.4:8085/MediaUploads/1/211/520140731170618/DPM202.mp4");
moviePlayer = new MPMoviePlayerController();
moviePlayer.ContentUrl = url;
moviePlayer.View.Frame = new CGRect((float)((NativeView.Bounds.Width - 600) / 2), (float)((NativeView.Bounds.Height - 450) / 2), 600, 400);
UIGraphics.EndImageContext();

回答2:

Try switching to AVPlayerViewController instead of MPMoviePlayerController. Throw this code inside your OnElementChanged method.

My renderer was a view renderer and not a page renderer so you might have to tweak it a bit.

if(Control == null)
{
    AVPlayerViewController avpvc;
    AVPlayer avp;

    var url = NSUrl.FromString("SOME URL HERE"); //or NSUrl.FromFile 
    avp = new AVPlayer(url);
    avpvc = new AVPlayerViewController();
    avpvc.Player = avp;
    avpvc.ShowsPlaybackControls = true;

    avp.Play();

    this.SetNativeControl(avpvc.View);
} 

来源：https://stackoverflow.com/questions/29672385/playing-a-video-with-xamarin-for-ios-broken-after-latest-update