AVPlayer Video Blank but Hear Sound - iphone

Question

I'm switching from MPMoviePlayerController to AVPlayer as I need finer grained control over video swapping. The .mov file I was playing with MPMoviePlayerController played fine, but after switching to AVPlayer I hear the audio from the video, but the video just shows the view background that I added the AVPlayerLayer to. Here's how I'm initializing the AVPlayer.
self.player = [[AVPlayer alloc] initWithURL:video];
AVPlayerLayer* playerLayer = [AVPlayerLayer playerLayerWithPlayer:self.player];
playerLayer.frame = self.playerContainer.bounds;
[self.playerContainer.layer addSublayer:playerLayer];
Then later I just issue a.
[self.player play];
When the video plays I hear the audio, but see no video. I also tried setting the zPosition to no luck.
playerLayer.zPosition = 1;

Answer 1

Found out it was a result of using AutoLayout. In the viewDidLoad the self.playerContainer.bounds is a CGRectZero.
I had to assign the playerLayer frame in the viewDidAppear to match the playerContainer.

Answer 2

Since we use AVPlayerLayer (a subclass of CALayer), we need to set the frame
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
self.avPlayerLayer.frame = self.movieContainerView.bounds;
}

Answer 3

Make sure you the statement that plays the video:
[self.player play]
is invoked from main dispatch queue like this (Swift 3):
DispatchQueue.main.async {
self.player.play()
}