Player swift crash app

Question

I have add Player-swift in my project to play video but when i pop that controller app getting crash with following log

Terminating app due to uncaught exception 'NSRangeException', reason: 'Cannot remove an observer for the key path "rate" from because it is not registered as an observer.'

any one have any idea? i have used this player https://github.com/piemonte/Player

Thanks in advance !

are you removed the `rate` observer in viewdisappear – Anbu.Karthik Sep 05 '17 at 09:50 — Anbu.Karthik, Sep 05 '17 at 09:50
@Anbu.Karthik no i have not changed anything – Hardik Baldha Sep 05 '17 at 11:52 — Hardik Baldha, Sep 05 '17 at 11:52

score 0 · Answer 1 · answered Sep 07 '17 at 08:52

0

Do not forget to unsubsribe from observing some property. For example if you subscribed for observing rate then to remove observing use

player.removeObserver(observer, forKeyPath: #keyPath(AVPlayer.rate))

answered Sep 07 '17 at 08:52

Ihar Katkavets

1,510
14
25

score 0 · Answer 2 · answered May 21 '18 at 12:32

First: check KVO basics.
Second: in objective-C you would the removing observers code into try-catch block and live happy. The apple's guide tell the same:

Asking to be removed as an observer if not already registered as one results in an NSRangeException. You either call removeObserver:forKeyPath:context: exactly once for the corresponding call to addObserver:forKeyPath:options:context:, or if that is not feasible in your app, place the removeObserver:forKeyPath:context: call inside a try/catch block to process the potential exception.

In swift there’s no KVO API call you can make to ask, “Is X observing key path Y of object Z?” There is some ways to workaround it.

Also check the one of the reasons of the crashes when removing the observer. Here is the quote:

"It" refers to the observer. -removeObserver:forKeyPath: raises this exception if told to remove an object that isn't currently registered as an observer. So what's happening is that a table view is trying to unregister as an observer from one of your objects that it unfortunately didn't previouly register as an observer for.

The usual cause of this is that you have a property that isn't KVO- compliant. Something accesses your 'foo' property and registers as an observer of that property, and also as an observer of the object that's the property's current value; you change the value of 'foo' without letting anyone know; the observer then later decides to stop observing, gets your 'foo' property, and removes itself as an observer of that object. But it's no longer the same object that it registered as an observer for...

Jignesh Mayani · Answer 3 · 2018-05-21T12:50:53.180

Take IBOutlet of Your UIView for Example

@IBOutlet var videoView:UIView!
var player:AVPlayer!

func buttonPressed()
{
    let videoURL = URL(fileURLWithPath: "your File Path")
    player = AVPlayer(url: videoURL)
    let playerLayer = AVPlayerLayer(player: player)
    playerLayer.videoGravity = .resizeAspect
    playerLayer.frame = videoView.bounds
    videoView.layer.addSublayer(playerLayer)
    player.play()
    player.actionAtItemEnd = .none

    NotificationCenter.default.addObserver(self, selector: #selector(self.playerItemDidReachEnd(_:));, name: .AVPlayerItemDidPlayToEndTime, object: player.currentItem)
}

@objc func playerItemDidReachEnd(_ notification: Notification?)
{
    let p = notification?.object as? AVPlayerItem
    p?.seek(to: kCMTimeZero)
}
override func viewWillDisappear(_ animated: Bool)
{
    NotificationCenter.default.removeObserver(self, name: .AVPlayerItemDidPlayToEndTime, object: player.currentItem)
}

Player swift crash app

3 Answers3