ios - swift invalidate timer doesn't work

Question

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.

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

That's my timer

func timerDidEnd(timer:NSTimer){
    createUnrepeatedAlarmWithUpdateInterval()
}

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!.invalidate()
    }
    self.timer = nil
    self.timer = NSTimer()
}

And that's how I stop my timer.

alarmManager.stopAlarm()
alarmManager.createUnrepeatedAlarmWithUpdateInterval()

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){
    ConnectionManager.sharedInstance.loadTrainings(settingsViewController.getServerSettings())
    createUnrepeatedAlarm(10)
}

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!.invalidate()
        timer = nil
    }

    if (unrepeatedTimer != nil)
    {
        unrepeatedTimer!.invalidate()
        unrepeatedTimer = nil
    }
}
}

Thats the whole code of this class. Maybe that helps :D

Answer 1

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!.invalidate()
    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).