我有一个按钮，它提出了AVPlayerViewController和我设法添加图片在pciture到我的AVPlayerViewController，所以我可以最小化它，现在一旦最小化，我想最大化它再次，但只要我这样做的AVPlayerViewController消失。我不打算使用故事板，我想通过编程来实现，因为在导航控制器中嵌入视图控制器可以解决这个问题，但我不想遵循这种方法
我添加了BackgroundMode功能，并在Appdelegate中勾选了PIP和

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        let audioSession = AVAudioSession.sharedInstance()
        do {
            try audioSession.setCategory(.playback)
            try audioSession.setActive(true, options: [])
        } catch {
            print("Setting category to AVAudioSessionCategoryPlayback failed.")
        }
        
        return true
    }

我的ViewController

class ViewController: UIViewController,AVPlayerViewControllerDelegate {
    
    var playerController : AVPlayerViewController!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
    }
    
    
    @IBAction func btnClicked(_ sender: Any) {
        if let videoURL = URL(string: "https://storage.googleapis.com/exoplayer-test-media-0/BigBuckBunny_320x180.mp4") {
            let player = AVPlayer(url: videoURL)
            
            playerController = AVPlayerViewController()
            
            NotificationCenter.default.addObserver(self, selector: #selector(ViewController.didfinishPlaying(note:)), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: player.currentItem)
            
            playerController.player = player
            
            playerController.allowsPictureInPicturePlayback = true
            
            playerController.delegate = self
            
            playerController.player?.play()
            
            self.present(playerController, animated: true, completion : nil)
            
        }
    }
    
    
  
    
}

只是为了创建一个简单的演示，我使用了storyboard，在我真实的的应用程序中我不使用它