How to make a AVPlayerViewController go to fullscreen programmatically?

AVPlayerViewController is a subclass of UIViewController, so it is presentable like any other view controller subclass. Are you able to use presentViewController:animated:completion?

self.avPlayerController.modalPresentationStyle = UIModalPresentationOverFullScreen;
[self presentViewController:self.avPlayerController animated:YES completion:nil];

This then shows the “Done” button in the top left-hand corner.