如何完全删除NSTimer ScheduledTimerWithTimeInterval

Question

I wave a time value inside NSUserDefaults , and when I'm reusing my ViewController my NSTimer adds +1 to Interval

here my update function:

func fireUpdatedLimit() {
        var endTimeSeconds = userDefaults.integerForKey("endTimeSeconds\(currentUserId!)")
        if endTimeSeconds > 0  {
            endTimeSeconds += 1
            userDefaults.setInteger(endTimeSeconds, forKey: "endTimeSeconds\(currentUserId!)")
        }
        self.timer =  NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: #selector(ViewController.updateLimit), userInfo: nil, repeats: true)
    }

and here what I've already tried:

weak var timer = NSTimer() 
weak var timer: NSTimer?

self.timer = nil 
self.timer.invalidate()

logic:

func updateLimit() {

        var timeLeft = userDefaults.integerForKey("endTimeSeconds\(currentUserId!)")
        foregroundAction() {
            self.lockedTimeLabel.hidden = false
            self.lockedImageView.hidden = false
        }
        self.lockedTimeLabel.text = String(fromTimeInterval: Double(timeLeft))
        if timeLeft <= 0 {
            print("ended")
            foregroundAction() {
                self.lockedImageView.hidden = true
                self.lockedTimeLabel.hidden = true
                self.mediaImageView.hidden = true
                self.followerImageView.hidden = true
            }
            self.reloadContent()
            userDefaults.setInteger(timeLeft, forKey: "endTimeSeconds\(currentUserId!)")
            self.timer!.invalidate()
        } else {
            timeLeft -= 1

            userDefaults.setInteger(timeLeft, forKey: "endTimeSeconds\(currentUserId!)")
        }
    }

Answer 1

If you set the timer to nil then the reference is broken and you can't invalidate it, so you must call invalidate first.

Ensure that you always check the reference and invalidate when you're going to create a new timer as that also breaks any reference to the old timer.

Also, never create a dummy / placeholder timer with Timer() , you require an optional reference ( ? ).