swift invalidate timer doesn't work

I have this problem for a few days now and I don’t get what I am doing wrong.

My application is basically just creating some timers. I need to stop them and create new ones. But at the moment stopping them doesn’t work.

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  • self.timer = NSTimer.scheduledTimerWithTimeInterval(timeInterval, target:self, selector: "timerDidEnd:", userInfo: "Notification fired", repeats: false)

    That’s my timer

    func timerDidEnd(timer:NSTimer){

    Because my timer didn’t want to stop I am currently using the unrepeated timer and start it myself after it stopped.

    func stopAlarm() {
        if self.timer != nil {
        self.timer = nil
        self.timer = NSTimer()

    And that’s how I stop my timer.


    I call the stopAlarm() function before creating a new timer.

    I really don’t know what I am doing wrong so I appreciate every answer 🙂

    class AlarmManager: ViewController{
    private var timer : NSTimer?
    private var unrepeatedTimer : NSTimer?
    private let notificationManager = NotificationManager()
    private var current = NSThread()
    private let settingsViewController = SettingsViewController()
    func createRepeatedAlarmWithUpdateInterval(){
        var timeInterval:NSTimeInterval = settingsViewController.getUpdateIntervalSettings()
        if timer == nil{
        timer = NSTimer.scheduledTimerWithTimeInterval(timeInterval,
            target: self,
            selector: "repeatedTimerDidEnd:",
            userInfo: "Notification fired",
            repeats: true)
    func repeatedTimerDidEnd(repeatedTimer:NSTimer){
    func createUnrepeatedAlarm(timeInterval:Double){
        unrepeatedTimer = NSTimer.scheduledTimerWithTimeInterval(timeInterval,
            target: self,
            selector: "unrepeatedTimerDidEnd:",
            userInfo: "Notification fired",
            repeats: false)
    func unrepeatedTimerDidEnd(unrepeatedTimer:NSTimer){
        notificationManager.createNotification(self, reminderType: NotificationManager.ITEMRATINGREMINDER)
        notificationManager.createNotification(self, reminderType: NotificationManager.ITEMREMINDER)
        print("UnrepeatedAlarm ended")
    func stopAlarm(){
        print("StopAlarm triggered")
        if (timer != nil)
            print("stoptimer executed")
            timer = nil
        if (unrepeatedTimer != nil)
            unrepeatedTimer = nil

    Thats the whole code of this class. Maybe that helps 😀

    Solutions Collect From Internet About “swift invalidate timer doesn't work”

    The usual way to start and stop a timer safely is

    var timer : NSTimer?
    func startTimer()
      if timer == nil {
        timer = NSTimer.scheduledTimerWithTimeInterval(timeInterval, target: self, selector: "timerFired", userInfo: nil, repeats: true)
    func stopTimer()
      if timer != nil {
        timer = nil

    startTimer() starts the timer only if it’s nil and stopTimer() stops it only if it’s not nil.

    You have only to take care of stopping the timer before creating/starting a new one.

    In Swift 3 replace

    • NSTimer with Timer,
    • NSTimer.scheduledTimerWithTimeInterval( with Timer.scheduledTimer(timeInterval:
    • selector: "timerFired" with selector: #selector(timerFired).