UIView 可以设定 autoresizingMask，当它的 superView 尺寸改变时，适应何种变化。
不过 CALayer 却没有这个属性，如和做到让 CALayer 和 UIView 一样？可以这样：
// in ViewController
- (void)viewWillLayoutSubviews
{
_playerLayer.frame = self.view.bounds;
}
// in View
- (void)layoutSublayersOfLayer:(CALayer *)layer
{
_playerLayer.frame = self.bounds;
}
这不是一个好的办法。
当当~
自定义一个 UIView，重写它的 + (Class)layerClass 方法，像这样
@interface RFPlayerLayerView : UIView
@end
@implementation RFPlayerLayerView
+ (Class)layerClass
{
return [AVPlayerLayer class];
}
@end
使用时设置一些参数，就可以完美拥有 UIView 的 autoresizingMask 的属性了
- （void)setup
{
_layerView = [[RFPlayerLayerView alloc] initWithFrame:rect];
_playerLayer = (AVPlayerLayer *)[_layerView layer];
_playerLayer.player = _player;
_playerLayer.videoGravity = AVLayerVideoGravityResizeAspect;
_layerView.autoresizingMask = UIViewAutoresizingFlexibleWidth|UIViewAutoresizingFlexibleHeight;
[self.view addSubview:_layerView];
}
CALayer: autoresizingMask,布布扣,bubuko.com
原文：http://www.cnblogs.com/ihojin/p/calayer-autoresizingmask.html