问题
I have updated my code to swift 4 in Xcode 9. Before that it was working fine. But now AVplayer is crashing at observers below is the code where it is crashing.
addObserver(self, forKeyPath: "player.currentItem.duration", options: [.new, .initial], context: &playerViewControllerKVOContext)
And the log is
Terminating app due to uncaught exception 'NSUnknownKeyException',reason: '[ addObserver: forKeyPath:@"player.currentItem.duration" options:5 context:0x10ff74ac8] was sent to an object that is not KVC-compliant for the "player" property.'
回答1:
Swift does not have the Key value observer of its own so for Swift 4 we have to add:
@objc dynamic
before the property whose value you need to observe. In your case it will be the AVPlayer instance. e.g.:
class MyPlayerCustomView: UIView {
@objc dynamic var myPlayer: AVPlayer?
}
Hope this solves your problem. It did solve mine!
来源：https://stackoverflow.com/questions/46419893/nsunknownkeyexception-was-sent-to-an-object-that-is-not-kvc-compliant-for-the