Using Swift 3 Stopping a scheduledTimer, Timer continue firing even if timer is nil

Question

We call startTimer function to start a timer. When we wanted to stop it we call stopTimerTest function but after we called stopTimer function the timerTestAction keeps firing. T

Answer 1

Make sure when you call StartTimer it is nil and if you call StartTimer twice without calling StopTimer. You will lose your original pointer and you can't stop it.

 var timer : Timer? = nil {
        willSet {
            timer?.invalidate()
        }
    }

Start and Stop timer like ...

func startTimer() {
    stopTimer()
    guard self.timer == nil else { return }
    self.timer = Timer.scheduledTimer(timeInterval: 10, target: self, selector: #selector(self.fetchData), userInfo: nil, repeats: true)
}

func stopTimer() {
    guard timer != nil else { return }
    timer?.invalidate()
    timer = nil
}