how do i have countdown timer in swift stackoverflow
@IBAction func start(sender: UIButton) {
self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: #selector(ViewController.update(_:)), userInfo: nil, repeats: true)
NSRunLoop.currentRunLoop().addTimer(self.timer, forMode: NSRunLoopCommonModes)
startTime = NSDate() // new instance variable that you would need to add.
}
func update() {
let elapsedTime = NSDate().timeIntervalSinceDate(startTime)
let currTime = totalTime - elapsedTime
//total time is an instance variable that is the total amount of time in seconds that you want
countDown.text = String(currTime)
if currTime < 0 {
timer.invalidate()
//do other stuff that you need to do when time runs out.
}
}