Is the function being called more than once? [duplicate] - ios

Question

This question already has an answer here:
Why is the title being repeated?
(1 answer)
Closed 7 years ago.
I am trying to add the song title and artist to a database every time the song changes. The program currently does that, but for some reason when I go to the next song, the same song is added more than once in the database, i.e. Song 1 is added 6 times in parse. Why is this happening and how can I fix it?
func applicationDidEnterBackground(application: UIApplication) {
print("entered background")
NSNotificationCenter.defaultCenter().addObserver(self, selector: "getNowPlayingItem", name: MPMusicPlayerControllerNowPlayingItemDidChangeNotification, object: nil)
musicPlayer.beginGeneratingPlaybackNotifications()
backgroundTask = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler({ () -> Void in
UIApplication.sharedApplication().endBackgroundTask(self.backgroundTask!)
self.backgroundTask = UIBackgroundTaskInvalid
})
}
func getNowPlayingItem() {
if let nowPlaying = musicPlayer.nowPlayingItem {
let title = nowPlaying[MPMediaItemPropertyTitle]
let artisttest = nowPlaying[MPMediaItemPropertyTitle]
if let artist = nowPlaying[MPMediaItemPropertyArtist] {
let objectPointer = PFObject(className: "Pointer")
let object = PFObject(className: "MasterSongs")
let query = PFQuery(className: "Pointer")
query.findObjectsInBackgroundWithBlock({
(objects: [AnyObject]?, error: NSError?) -> Void in
var objectIDs = objects as! [PFObject]
for i in 0...objectIDs.count-1{
self.Parsearray.append((objectIDs[i].valueForKey("title") as? String)!)
}
if self.Parsearray.contains(title! as! String){
print("already in db")
}else{
objectPointer["title"] = title
objectPointer["user"] = PFUser.currentUser()
objectPointer["artist"] = artist
objectPointer.saveInBackground()
//parseClass.saveInBackgroundWithBlock{(success: Bool, error: NSError!) -> Void in
objectPointer.saveInBackgroundWithBlock({ (success: Bool, error: NSError?) -> Void in
if success == false {
print(error)
} else {
print("Posted succesfully")
}
})
}
})
}
if(artisttest == nil){
let objectPointer = PFObject(className: "Pointer")
let query = PFQuery(className: "Pointer")
query.findObjectsInBackgroundWithBlock({
(objects: [AnyObject]?, error: NSError?) -> Void in
var objectIDs = objects as! [PFObject]
for i in 0...objectIDs.count-1{
self.Parsearray.append((objectIDs[i].valueForKey("title") as? String)!)
}
if self.Parsearray.contains(title! as! String){
print("already in db")
}else{
objectPointer["title"] = title
objectPointer["user"] = PFUser.currentUser()
objectPointer["artist"] = "No artist found :("
objectPointer.saveInBackground()
}
})
}
}
}
func applicationWillEnterForeground(application: UIApplication) {
NSNotificationCenter.defaultCenter().removeObserver(self)
}

Answer 1

One thing I notice is that you add an observer for MPMusicPlayerControllerNowPlayingItemDidChangeNotification every time applicationDidEnterBackground is called.
You didn't include the applicationDidEnterForeground function - but hopefully you are removing those observer there. If you don't remove the observers, it would cause the getNowPlayingItem selector to be called for each applicationDidEnterBackground. So 6 applicationDidEnterBackground = 6 getNowPlayingItem.