Question

我在应用的登录页面上循环播放视频。我按照这个Youtube教程使其工作loop video in view controller

问题是当应用程序进入后台时，如果我不立即回来，当我回来时，视频会被冻结。

根据应该发生的Apple Docs。

我尝试使用NotificationCenter的Notification.Name.UIApplicationWillResignActive，但这不起作用。

如果应用从后台返回，如何让视频继续播放？

var player: AVPlayer!
var playerLayer: AVPlayerLayer!

override func viewDidLoad() {
        super.viewDidLoad()

        configurePlayer()
}


@objc fileprivate func configurePlayer(){

        let url = Bundle.main.url(forResource: "myVideo", withExtension: ".mov")

        player = AVPlayer.init(url: url!)
        playerLayer = AVPlayerLayer(player: player!)
        playerLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
        playerLayer.frame = view.layer.frame


        player.actionAtItemEnd = AVPlayerActionAtItemEnd.none

        player.play()

        view.layer.insertSublayer(playerLayer, at: 0)

        NotificationCenter.default.addObserver(self, selector: #selector(playerItemReachedEnd), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: player.currentItem)

        NotificationCenter.default.addObserver(self, selector: #selector(playerItemReachedEnd), name: Notification.Name.UIApplicationWillResignActive, object: player.currentItem)

    }

@objc fileprivate func playerItemReachedEnd(){
        player.seek(to: kCMTimeZero)
    }

Answer 1

根据Apple Docs播放视频并将应用程序发送到后台时，播放器会自动暂停：

他们要做的是在应用程序进入后台时删除AVPlayerLayer（设置为nil），然后在前台进行重新初始化时使用

他们说处理此问题的最佳方式是applicationDidEnterBackground和applicationDidBecomeActive：

我使用NSNotification来监听背景和前景事件，并设置暂停播放器和放大器的功能。将playerLayer设置为nil（均为背景事件），然后重新初始化playerLayer＆amp;为前景事件播放了播放器。这些是我使用的通知.UIApplicationWillEnterForeground和.UIApplicationDidEnterBackground

我发现的是，出于某种原因，如果您长按主页按钮，弹出的屏幕显示“我可以帮助您”，如果您再次按“主页”按钮回到你的应用程序后，视频将被冻结，并使用上面的2个通知不会阻止它。我发现阻止此操作的唯一方法是还使用通知.UIApplicationWillResignActive和.UIApplicationDidBecomeActive。如果您不在上述通知中添加这些内容，那么您的视频将在长按按住主页按钮后冻结。我发现阻止所有冻结方案的最佳方法是使用所有4个通知。

我必须做的两件事与上面的代码不同的是将player和playerLayer类变量设置为可选项而不是隐式展开的选项，我还在AVPlayer类中添加了一个扩展，以检查它是否在iOS中播放9或以下。在iOS 10及更高版本中，有一种内置方法.timeControlStatus AVPlayer timer status

上面的代码：

var player: AVPlayer?
var playerLayer: AVPlayerLayer?

在iOS 9或更低版本中将AVPlayer的扩展名添加到check the state of the AVPlayer：

import AVFoundation

extension AVPlayer{

    var isPlaying: Bool{
        return rate != 0 && error == nil
    }
}

以下是完整的代码：

var player: AVPlayer?
var playerLayer: AVPlayerLayer? //must be optional because it will get set to nil on background event

override func viewDidLoad() {
    super.viewDidLoad()

    // background event
    NotificationCenter.default.addObserver(self, selector: #selector(setPlayerLayerToNil), name: .UIApplicationDidEnterBackground, object: nil)

    // foreground event
    NotificationCenter.default.addObserver(self, selector: #selector(reinitializePlayerLayer), name: .UIApplicationWillEnterForeground, object: nil)

   // add these 2 notifications to prevent freeze on long Home button press and back
    NotificationCenter.default.addObserver(self, selector: #selector(setPlayerLayerToNil), name: Notification.Name.UIApplicationWillResignActive, object: nil)

    NotificationCenter.default.addObserver(self, selector: #selector(reinitializePlayerLayer), name: Notification.Name.UIApplicationDidBecomeActive, object: nil)

    configurePlayer()
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    // this is also for the long Home button press
    if let player = player{
        if #available(iOS 10.0, *) {
            if player.timeControlStatus == .paused{
                player.play()
            }
        } else {
            if player.isPlaying == false{
                player.play()
            }
        }
    }
}

@objc fileprivate func configurePlayer(){

    let url = Bundle.main.url(forResource: "myVideo", withExtension: ".mov")

    player = AVPlayer.init(url: url!)
    playerLayer = AVPlayerLayer(player: player!)
    playerLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
    playerLayer?.frame = view.layer.frame

    player?.actionAtItemEnd = AVPlayerActionAtItemEnd.none

    player?.play()

    view.layer.insertSublayer(playerLayer!, at: 0)

    NotificationCenter.default.addObserver(self, selector: #selector(playerItemReachedEnd), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: player.currentItem)
}

@objc fileprivate func playerItemReachedEnd(){
     // this works like a rewind button. It starts the player over from the beginning
     player?.seek(to: kCMTimeZero)
}

 // background event
@objc fileprivate func setPlayerLayerToNil(){
    // first pause the player before setting the playerLayer to nil. The pause works similar to a stop button
    player?.pause()
    playerLayer = nil
}

 // foreground event
@objc fileprivate func reinitializePlayerLayer(){

    if let player = player{

        playerLayer = AVPlayerLayer(player: player)

        if #available(iOS 10.0, *) {
            if player.timeControlStatus == .paused{
                player.play()
            }
        } else {
            // if app is running on iOS 9 or lower
            if player.isPlaying == false{
                player.play()
            }
        }
    }
}

不要忘记向AVPlayer添加isPlaying扩展

Answer 2

接受的答案对我不起作用。我的“欢迎”视频在某些情况下会随机暂停。

这是做什么的：
背景：由于当应用程序“ resignsActive”或进入“背景”时，player和playerLayer对象不会被破坏（可以通过观察它们各自的通知来观察它们的状态来进行验证）叫）我推测将这些对象中的任何一个都设置为nil，然后在进入背景或前景时将它们重新初始化是不必要的。

我只会在播放器对象进入前景时再次播放它。

var player: AVPlayer?
var playerLayer: AVPlayerLayer?

在ViewDidLoad中，我配置播放器对象。

override func viewDidLoad() {
  configurePlayer()
}

configurePlayer（）函数在下面定义

private func configurePlayer() {
  guard let URL = Bundle.main.url(forResource: "welcome", withExtension: ".mp4") else { return }

  player = AVPlayer.init(url: URL)
  playerLayer = AVPlayerLayer(player: player)
  playerLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
  playerLayer?.frame = view.layer.frame

  player?.actionAtItemEnd = AVPlayerActionAtItemEnd.none
  playItem()

  setupPlayNotificationItems()
}

这是辅助函数的实现

private func setupPlayNotificationItems() {
  NotificationCenter.default.addObserver(self,
                                        selector: #selector(restartPlayerItem),
                                        name: NSNotification.Name.AVPlayerItemDidPlayToEndTime,
                                        object: player?.currentItem)
  NotificationCenter.default.addObserver(self,
                                        selector: #selector(playItem),
                                        name: .UIApplicationWillEnterForeground,
                                        object: nil)
}

@objc private func playItem() {
  // If you please, you can also restart the video here
  restartPlayerItem()

  player?.play()

  if let playerlayer = playerLayer {
    view.layer.insertSublayer(playerlayer, at: 0)
  }
}

@objc func restartPlayerItem() {
  player?.seek(to: kCMTimeZero)
}

Answer 3

添加观察者

func addPlayerNotifications() {
    NotificationCenter.default.addObserver(self, selector: #selector(playerItemDidPlayToEnd), name: .AVPlayerItemDidPlayToEndTime, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(applicationWillEnterForeground), name: .UIApplicationWillEnterForeground, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(applicationDidEnterBackground), name: .UIApplicationDidEnterBackground, object: nil)
}

删除观察者

func removePlayerNotifations() {
    NotificationCenter.default.removeObserver(self, name: .AVPlayerItemDidPlayToEndTime, object: nil)
    NotificationCenter.default.removeObserver(self, name: .UIApplicationWillEnterForeground, object: nil)
    NotificationCenter.default.removeObserver(self, name: .UIApplicationDidEnterBackground, object: nil)
}

方法

// Player end.
@objc  func playerItemDidPlayToEnd(_ notification: Notification) {
    // Your Code.
    player.seek(to: kCMTimeZero)
}

//App enter in forground.
@objc func applicationWillEnterForeground(_ notification: Notification) {
      player.play()
}

//App enter in forground.
@objc func applicationDidEnterBackground(_ notification: Notification) {
      player.pause()
}

试试此代码

Answer 4

我在 Swift 4.3 中找到了一个适用于我的简单解决方案。我刚刚创建了一个观察器，用于观察应用程序何时在覆盖的ViewDidLoad中进入背景，何时进入前景。

NotificationCenter.default.addObserver(self, selector:#selector(VideoViewController.shutItDown), name: UIApplication.didEnterBackgroundNotification, object: UIApplication.shared)
NotificationCenter.default.addObserver(self, selector:#selector(VideoViewController.refresh), name: UIApplication.willEnterForegroundNotification, object: nil)

然后，我在类中具有以下由观察者调用的方法：

@objc func refresh() {
    setupVideo()
}

@objc func shutItDown() {
    self.newLayer.removeFromSuperlayer()
}

其中newLayer是我的AVLayer，已作为子图层添加到我的VideoView中。只是为了更加冗长，我为我的视频设置添加了代码，以确保即使您的外观看起来完全不同，所有内容都可以理解。

private func setupVideo() {

    self.path = URL(fileURLWithPath: Bundle.main.path(forResource: "coined", ofType: "mov")!)
    self.player = AVPlayer(url: self.path)

    self.newLayer = AVPlayerLayer(player: self.player)
    self.newLayer.frame = self.videoView.frame
    self.videoView.layer.addSublayer(newLayer)
    self.newLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill

    self.player.play()

    self.videoView.bringSubviewToFront(continueButton)
    self.videoView.bringSubviewToFront(settingsButton)
}

此方法的“缺点”是，每次从后台转到前景时，视频都会重新启动。在我的情况下，这是可以接受的，但在您的情况下可能不可接受。这是因为当您进入背景时，AVLayer被删除，并且每次您进入前景时，都会在videoView上放置一个新的AVLayer。为了防止呈现快照错误（即克服“冻结”），必须删除旧的AVLayer。

Answer 5

Tsonono答案很好用，我只是用它来修复冻结的视频。

一方面，不摆脱他在谈论的缺点（每次进入前景时，视频都会重新启动），只需使用这两种方法（shutdowndown方法中的暂停播放器和refresh方法中的播放器）调用播放器本身：< / p>

@objc func refresh() {
self.player?.play()
@objc func shutItDown() {
self.player?.pause()

}

当应用程序从后台回来时，Swift iOS -AVPlayer视频冻结/暂停

5 个答案: