AVPlayerLayer 设置自动布局

如果要设置playerLayer的布局，目前iOS不支持layer设置AutoLayout也不支持autoresizingMask，所以无法给playerLayer设置约束，当然可以采用原始的方法，就是在viewDidLayoutSubviews中再次设置playerLayer的frame，但是这样在屏幕旋转时会有一片短暂的空白区域，虽然很快就消失了，但是这样效果不是很好。

解决方案: 通过UIView来处理，自定义一个UIView的子类，设置这个view的layerClass为AVPlayerLayer类型，然后直接使用这个子类的layer作为AVPlayerLayer，那么此时不需要设置playerLayer的frame，设置这个view的约束或frame即可

以下界面我是通过XIB搭建界面
#import "XYVideoPlayer.h"
#import <AVFoundation/AVFoundation.h>

@implementation XYVideoPlayer

+ (Class)layerClass {
    return [AVPlayerLayer class];
}

@end

#import "ViewController.h"
#import <MobileCoreServices/MobileCoreServices.h>
#import "XYVideoPlayer.h"

@interface ViewController ()

@property (weak, nonatomic) IBOutlet XYVideoPlayer *videoLayer;
@end
@implementation ViewController
- (void)viewDidLoad {
    [super viewDidLoad];

    self.videoLayer.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
    
    self.asset = [AVAsset assetWithURL:videoURL];
    
    AVPlayerItem *playerItem = [[AVPlayerItem alloc] initWithAsset:self.asset];
    
    self.player = [AVPlayer playerWithPlayerItem:playerItem];
    // 将player输出到显示动画层playerLayer
    self.playerLayer = (AVPlayerLayer *)self.videoLayer.layer;
    [self.playerLayer setPlayer:self.player];
}