概述

本文中Demo下載地址。
如果你想自定義播放器實現畫中畫，就可以采用 AVKit 框架中的AVPictureInPictureController類。 如果你想基礎的實現畫中畫可以參考AVPlayerViewController實現畫中畫 。

使用AVPictureInPictureController實現畫中畫步驟

1. 創建一個項目，添加Background modes；選擇Target > Signing & Capabilities項，點擊“+ Capability”添加Background modes，把“Audio，AirPlay，and Picture in picture”打上對勾。如下圖：

   
   
   23.png

2. 配置Audio Playback Behavior，需要設置App 的AVAudioSession的Category為playback模式，示例代碼如下：

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

3. 創建一個新的AVPictureInPictureController對象，向它傳遞一個對顯示視頻內容的AVPlayerLayer的引用。需要對AVPictureInPictureController對象必須強引用才能使PiP正常功能。設置AVPictureInPictureController示例代碼如下：

    var playerLayer : AVPlayerLayer = AVPlayerLayer()
    var player : AVPlayer?
    var pictureInPictureController : AVPictureInPictureController?

    //設置PictureInPicture
    func setupPictureInPicture() {
        guard let videoURL = Bundle.main.url(forResource: "v1", withExtension: "MP4") else {
            return
        }
        //設置AVPlayerLayer
        playerLayer.frame = self.view.frame
        playerLayer.videoGravity = .resizeAspect
        self.view.layer.addSublayer(playerLayer)        

        //設置AVPlayer
        let asset = AVURLAsset(url: videoURL)
        let playerItem = AVPlayerItem(asset: asset)
        player = AVPlayer(playerItem: playerItem)
        if let player = player {
            playerLayer.player = player
        }
        
        // Ensure PiP is supported by current device.  isPictureInPictureSupported()判斷設備是否支持畫中畫
        if AVPictureInPictureController.isPictureInPictureSupported() {
            // Create a new controller, passing the reference to the AVPlayerLayer.
            pictureInPictureController = AVPictureInPictureController(playerLayer: playerLayer)
            pictureInPictureController?.delegate = self //設置代理
        } else {
            print("當前設備不支持PiP")
        }
        player?.play()
    }

4. 使用AVPictureInPictureController的pictureInPictureButtonStartImage和pictureInPictureButtonStopImage，我們可以創建一個Button，然后把Button的image設置為pictureInPictureButtonStartImage或者pictureInPictureButtonStopImage。示例代碼如下：

    func addPipButton() {
        //設置開啟或者關閉pictureInPicture
        pipButton = UIButton(type: .system)
        //系統默認的pictureInPictureButtonStartImage
        let startImage = AVPictureInPictureController.pictureInPictureButtonStartImage
        pipButton.setImage(startImage, for: .normal)
        pipButton.frame = CGRect(x: 10, y: 20, width: 40, height: 40)
        pipButton.addTarget(self, action: #selector(clickPipButton(_:)), for: .touchUpInside)
        self.view.addSubview(pipButton)
    }

    
    @objc func clickPipButton(_ sender: Any) {
        //判斷Pip是否在Active狀態
        guard let isActive = pictureInPictureController?.isPictureInPictureActive else { return }
        if (isActive) {
           //停止畫中畫
            pictureInPictureController?.stopPictureInPicture()
            let startImage = AVPictureInPictureController.pictureInPictureButtonStartImage
            pipButton.setImage(startImage, for: .normal)
        } else {
            //啟動畫中畫
            pictureInPictureController?.startPictureInPicture()
            //系統默認的pictureInPictureButtonStopImage
            let stopImage = AVPictureInPictureController.pictureInPictureButtonStopImage
            pipButton.setImage(stopImage, for: .normal)
        }
    }

5. 然后 build and run你的項目即可實現一個自定義的畫中畫Demo。
   效果圖如下：

   
   
   25.PNG

AVPictureInPictureController的一些常用方法：

//開始啟動畫中畫
open func startPictureInPicture()

//停止畫中畫
open func stopPictureInPicture()

//當前是否可以使用畫中畫
open var isPictureInPicturePossible: Bool { get }

//當前是否處于畫中畫狀態
open var isPictureInPictureActive: Bool { get }

//當前畫中畫是否被掛起
open var isPictureInPictureSuspended: Bool { get }

//這可用于臨時強制播放強制內容（如法律術語或廣告）
@available(iOS 14.0, *)
open var requiresLinearPlayback: Bool

AVPictureInPictureControllerDelegate的代理方法

extension ViewController : AVPictureInPictureControllerDelegate {
    func pictureInPictureControllerWillStartPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        print("將要開始PictureInPicture的代理方法")
    }

    func pictureInPictureControllerDidStartPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        print("已經開始PictureInPicture的代理方法")
    }

   
    func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController, failedToStartPictureInPictureWithError error: Error) {
        print("啟動PictureInPicture失敗的代理方法")
    }

    
    func pictureInPictureControllerWillStopPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        print("將要停止PictureInPicture的代理方法")
    }

    
    func pictureInPictureControllerDidStopPictureInPicture(_ pictureInPictureController: AVPictureInPictureController) {
        print("已經停止PictureInPicture的代理方法")
    }

    
    func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController, restoreUserInterfaceForPictureInPictureStopWithCompletionHandler completionHandler: @escaping (Bool) -> Void) {
        //此方法執行在pictureInPictureControllerWillStopPictureInPicture代理方法之后，在pictureInPictureControllerDidStopPictureInPicture執行之前。 但是點擊“X”移除畫中畫時，不執行此方法。
        print("PictureInPicture停止之前恢復用戶界面")
    }
}