iOS画中画播放视频

画中画功能iOS9就有了，以前只能在iPad上使用，iOS14开始在iPhone上也可以使用了，一直没有这方面的需求也没有具体的研究，不过毕竟是苹果官方的东西，相信实现起来不会麻烦，有2种办法来实现。前提都需要工程配置一定要对！！！

工程配置

配置BackgroundMode

//  开启后台播放权限
[[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionAllowBluetooth error:nil];
[[AVAudioSession sharedInstance] setActive:YES error:nil];

1. 使用AVPlayerViewController

如果使用的是AVPlayerViewController，只要AVAudioSession和BackgroundMode配置对就默认支持的,不用做其他任何操作。虽然很简单，但是相信很少人会直接用这个方式，几乎所有的项目都会自定义播放器，而不是直接使用系统的这个全屏播放器。

2. 使用AVPictureInPictureController

使用AVPictureInPictureController承接自己写的播放器的AVPlayerLayer即可实现，先放出来一个官方链接。可以直接去看相关API。
在API中可以看到有一个根据AVPlayerLayer来初始化Controller的方法：

/*!
    @method     initWithPlayerLayer:
    @param      playerLayer
                The player layer from which to source the media content for the Picture in Picture controller.
    @abstract   Initialize the picture in picture controller with a player layer.
 */
- (nullable instancetype)initWithPlayerLayer:(AVPlayerLayer *)playerLayer;

我们就在ViewController中简单粗暴的来一个AVPlayer播放一个视频尝试一下，刚开始的思路是这样的，先播放视频，当用户将要退到后台的时候，初始化AVPictureInPictureController并且启动画中画，后来实测发现这样是行不通，初始化AVPictureInPictureController的动作必须提前，然后在需要开启或者停止画中画功能，下面的代码是实现了在播放视频的时候已经初始化了AVPictureInPictureController，然后在应用将要退到后台的时候开启画中画播放视频，用户回到前台后停止画中画，AVPictureInPictureControllerDelegate中有一些相关的代理方法，全是可选实现，基本上用不到，可以根据自己的需要进行实现：

#import 
@interface ViewController ()
@property(nonatomic,strong)AVPlayerItem *playItem;
@property(nonatomic,strong)AVPlayer *player;
@property(nonatomic,strong)AVPlayerLayer *playerLayer;
@property(nonatomic,strong)AVPictureInPictureController *pictureInPictureController;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    
//    https://qiniu.hongwan.com.cn/hongwan/v/1982wi5b4690f4rqbd9kk.mp4  横屏
//    https://qiniu.hongwan.com.cn/hongwan/v/990g76sj2wvedbs53vji.mp4   竖屏
    
    [[AVAudioSession sharedInstance] setCategory:AVAudioSessionCategoryPlayback withOptions:AVAudioSessionCategoryOptionAllowBluetooth error:nil];
    [[AVAudioSession sharedInstance] setActive:YES error:nil];

    NSString *urlStr  =@"https://qiniu.hongwan.com.cn/hongwan/v/990g76sj2wvedbs53vji.mp4";
    self.playItem = [[AVPlayerItem alloc] initWithURL:[NSURL URLWithString:urlStr]];
    self.player = [[AVPlayer alloc] initWithPlayerItem:self.playItem];
    _playerLayer = [AVPlayerLayer playerLayerWithPlayer:_player];
     _playerLayer.frame = self.view.frame;
    _playerLayer.videoGravity = AVLayerVideoGravityResizeAspect;
    [self.view.layer addSublayer:_playerLayer];
    [self.playItem addObserver:self forKeyPath:@"status" options:NSKeyValueObservingOptionNew context:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(willResignActive) name:UIApplicationWillResignActiveNotification object:nil];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didBecomeActive) name:UIApplicationDidBecomeActiveNotification object:nil];
//   监听实现循环播放
    [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(loopPlay:) name:AVPlayerItemDidPlayToEndTimeNotification object:self.player.currentItem];

    self.pictureInPictureController = [[AVPictureInPictureController alloc] initWithPlayerLayer:self.playerLayer];
    self.pictureInPictureController.delegate = self;
}
-(void)loopPlay:(NSNotification *)notification
{
    if (!notification.object) {
        return;
    }
    AVPlayerItem *item = (AVPlayerItem *)notification.object;
    __weak __typeof(&*self)weakSelf = self;
    [item seekToTime:kCMTimeZero completionHandler:^(BOOL finished) {
        if (finished) {
            [weakSelf.player play];
        }
    }];

}
-(void)willResignActive
{
    if ([AVPictureInPictureController isPictureInPictureSupported]) {
        if (self.pictureInPictureController.isPictureInPictureActive) {
            [self.pictureInPictureController stopPictureInPicture];
        } else {
            [self.pictureInPictureController startPictureInPicture];
        }
    }
}
-(void)didBecomeActive
{
    if ([AVPictureInPictureController isPictureInPictureSupported]) {
        if (self.pictureInPictureController.isPictureInPictureActive) {
            [self.pictureInPictureController stopPictureInPicture];
        }
    }
}
#pragma mark -------播放属性监听--------
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if ([keyPath isEqualToString:@"status"]) {
        switch (self.playItem.status) {
            case AVPlayerStatusReadyToPlay:
                if (!self.player.timeControlStatus || self.player.timeControlStatus != AVPlayerTimeControlStatusPaused) {
                    [self.player play];
                }
                break;
            default:
                break;
        }
    }
}

可能有的同学会用到一个很流行的视频播放框架ZFPlayer，需要将实现ZFPlayerMediaPlayback协议的PlayerManager，将内部的avLayer抛出来，然后用这个layer来初始化AVPictureInPictureController即可。

以上就是项目中简单实现画中画播放视频的完整流程