Starting timer on button click in swift - ios

Question

Ive created a timer in swift to move a UISlider from one end to another again and again when a button is pressed. But I'm always getting a breakpoint at the timer line, although everything should be right.
#IBAction func setSliderValue(_ sender: UIButton){
mytimer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
}
func timerAction(){
let Range = slider.maximumValue - slider.minimumValue;
let Increment = Range/100;
let newval = slider.value + Increment;
if(Increment >= slider.maximumValue)
{
slider.setValue(newval, animated: true)
}
else
{
slider.setValue(0, animated: true)
}
}

Answer 1

The check of your function is incorrect.
func timerAction(){
let range = slider.maximumValue - slider.minimumValue
let increment = range/100
let newval = slider.value + increment
if newval <= slider.maximumValue {
slider.setValue(newval, animated: true)
} else {
slider.setValue(slider.minimumValue, animated: true)
}
}
Also, in your event handler, should invalidate the timer (if it's not nil) first before instancing a new one.

Answer 2

Its working now with the following code, though the slider is only moving from left to right until it gets invalidated.
#IBAction func setSliderValue(_ sender: UIButton){
mytimer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(timerAction), userInfo: nil, repeats: true)
/*slider.setValue(100, animated: true)
print("The value of the slider is now \(slider.value)")
sliderValue = Int(slider.value)*/
}
func timerAction(){
let Range = slider.maximumValue - slider.minimumValue;
let Increment = Range/100;
let newval = slider.value + Increment;
if(Increment <= slider.maximumValue)
{
slider.setValue(newval, animated: true)
print("The value of the slider is now \(slider.value)")
sliderValue = Int(slider.value)
}
else if (Increment >= slider.minimumValue)
{
slider.setValue(newval, animated: true)
}
}

Answer 3

Hope this helps if someone else needs help on a task "starting a count down timer on a button click".
Timer itself has to be declared inside of the button code and additionally create a Obj-C function to update the timer that will be connected trough the #selector.
class ViewController: UIViewController {
var myTimer = Timer()
var secondsToCount = 100
#IBAction func buttonTapped(_ sender: UIButton) {
myTimer.invalidate()
myTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateTimer), userInfo: nil, repeats: true)
}
#objc func updateTimer() {
secondsToCount -= 1
timerDisplayed.text = String(secondsToCount)
}
}
timerDisplayed is a label that I connected to see the value of the timer on the screen of the app.
SWIFT 5.3 & Xcode 12.0.1