Error when setting UISlider's Min and Max values - ios

Question

I am playing videos from the user's library in my app. I use this method in ViewDidLoad() to get the video:
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()
}
})
Inside the addObserversForVideo() I set different observers to update a slider that controls the video and also set its min and max values:
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)
})
Now, the problem is that I sometimes get this error which crashes my app:
'NSInternalInconsistencyException', reason: 'Attempting to set a
slider's minimumValue (0.000000) to be larger than the maximumValue
(nan)'
I don't understand why this happens as I am checking the currentItem to be non-nil with a guard statement at the beginning, and also I am setting minimum value after the maximum value. I would appreciate it if someone can help me out.

Answer 1

Thanks to #TonyNguyen I could fix the problem in one line:
guard currentItem.status.rawValue == AVPlayerItem.Status.readyToPlay.rawValue else {return}

Answer 2

You need to guard against two additional things:
currentPlayer.currentItem.status == .readyToPlay
currentPlayer.currentItem.duration >= CMTime.zero

Answer 3

In my periodicTimeObserver I change the (time) to seconds then check if the value is NaN or Infinite before updating anything.
_ = 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
})