//self.playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
self.playerLayer.videoGravity = AVLayerVideoGravityResizeAspect;
//self.playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
self.playerLayer.videoGravity = AVLayerVideoGravityResizeAspect;