NSNotification being fired off more then one time? - ios

Question

I am creating a sample player for a test project. I created a NSNotification to call a function to play the next audio track inside an array. The issue is the notification calls this function about 8 times in a row? I have no idea why this is occurring. Here is my code and thanks for the help!
let player = AVPlayer()
var urlPlayerItems = [String]()
var currentTrack: Int = 0
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
// Checks to see if player reached end
NotificationCenter.default.addObserver(self,
selector: #selector(PlayerViewController.autoplayNextTrack(notification:)),
name: NSNotification.Name.AVPlayerItemDidPlayToEndTime,
object: player.currentItem)
}
func playTrack() {
if urlPlayerItems.count > 0 {
let newMovieURL = URL(string: urlPlayerItems[currentTrack])!
asset = AVURLAsset(url: newMovieURL, options: nil)
player.play()
}
}
func autoplayNextTrack(notefication: NSNotification) {
if (currentTrack + 1) >= urlPlayerItems.count {
currentTrack = 0
} else {
currentTrack += 1
}
playTrack()
}

Answer 1

Aside from the fact that an observer shouldn't be set multiple times, i think that you should reset the player to zero right before calling the play function again
func autoplayNextTrack(notefication: NSNotification) {
player.seekToTime(kCMTimeZero)
if (currentTrack + 1) >= urlPlayerItems.count {
currentTrack = 0
} else {
currentTrack += 1
}
playTrack()
}

Answer 2

If you add your observers in viewDidAppear method, you need to make sure you only add them ONCE. the viewDidAppear methods will get called multiple times.
Easy way is just to make a BOOL and flag it when you have added/removed it .
EDIT:
Also, I don't see any method where you remove the observer anywhere in your code, make sure you remove it too when you want to stop observing.
Example:
deinit {
NSNotificationCenter.defaultCenter().removeObserver(self)
}
or in your viewWillDissapear method.