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 <AVKit/AVKit.h>
@interface ViewController ()<AVPictureInPictureControllerDelegate>
@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<NSString *,id> *)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
