设置 UISlider 的最小值和最大值时出错

Question

我在应用程序中正在从用户库中播放视频。我在ViewDidLoad()中使用此方法获取视频：

fileprivate let imageManager = PHImageManager()
fileprivate var playerLayer: AVPlayerLayer?
fileprivate var player:AVPlayer?
fileprivate var videoView:UIView?
imageManager.requestPlayerItem(forVideo: videoAsset, options: options, resultHandler: { playerItem, info in
            DispatchQueue.main.sync {
                guard self.playerLayer == nil else { return }
                self.player = AVPlayer(playerItem: playerItem)
                self.playerLayer = AVPlayerLayer(player: self.player)
                self.videoView = UIView(frame: self.view.frame)
                self.videoView?.contentMode = .scaleAspectFit
                self.playerLayer?.videoGravity = AVLayerVideoGravity.resizeAspect
                self.playerLayer?.frame = self.videoView!.layer.bounds
                self.videoView!.layer.addSublayer(self.playerLayer!)
                self.photoScrollView.addSubview(self.videoView!)
                self.addObserversForVideo()
            }
        })

在Addobserversforvideo((中，我设置了不同的观察者以更新控制视频的滑块，还设置了其最小值和最大值：

        guard let currentPlayer = player else {return}
        guard let currentItem = currentPlayer.currentItem else {return}
        NotificationCenter.default.addObserver(self,
                                               selector: #selector(self.playerFinishedPlayingVideo),
                                               name: NSNotification.Name.AVPlayerItemDidPlayToEndTime,
                                               object: nil)
        let interval = CMTime(seconds: 0.5, preferredTimescale: CMTimeScale(NSEC_PER_SEC))
        _ = playerLayer?.player?.addPeriodicTimeObserver(forInterval: interval, queue: DispatchQueue.main, using: { [weak self] (time) in
            self?.videoSlider.maximumValue = Float(currentItem.duration.seconds)
            self?.videoSlider.minimumValue = 0.0
            self?.videoSlider.value = Float(currentItem.currentTime().seconds)
            self?.videoElapsedTimeLabel.text = self?.getStringFromCMTime(time: currentItem.currentTime())
            let remainingTime = currentItem.duration - currentItem.currentTime()
            self?.videoRemainingTimeLabel.text = self?.getStringFromCMTime(time: remainingTime)
        })

现在，问题是i 有时获得此错误崩溃了我的应用程序：

'nsinternalinconsistencyException'，原因：'试图设置一个 滑块的最小值(0.000000(大于最大值 (nan('

我不明白为什么会发生这种情况，因为我在开始时检查了currentItem是非nil的，并且在最大值之后，我也将最小值设置为最小值。如果有人可以帮助我，我会很感激。

Answer 1

感谢@tonynguyen，我可以一行解决该问题：

    guard currentItem.status.rawValue == AVPlayerItem.Status.readyToPlay.rawValue else {return}

Answer 2

您需要防止另外两件事：

• currentPlayer.currentItem.status == .readyToPlay
• currentPlayer.currentItem.duration >= CMTime.zero

Answer 3

在我的periodicTimeObserver中，我将(time)更改为秒，然后在更新任何内容之前检查值是NaN还是Infinite。

_ = player?.addPeriodicTimeObserver(forInterval: interval, queue: DispatchQueue.main, using: { [weak self] (time) in
    let seconds = CMTimeGetSeconds(time)
            
    guard !(seconds.isNaN || seconds.isInfinite) else {
        return
    }
    // the rest of your code
})