All digits not shown in timer countdown

Question

While coming to a view I call a function to load a timer like so...

var count = 10

 func startTimer() {
         timer = Timer.scheduledTimer(timeInterval: 0.4, target: self, selector: #selector(self.update), userInfo: nil, repeats: true)
  }

and update function is given as..

@objc func update() {
    while (count != 0) {
      count -= 1
      countdownLabel.text = "\(count)"

    }
     timer.invalidate()
  }

But what happens is when I come to this view, straightaway the number 0 is shown as opposed to ideally displaying all numbers in the sequence 9,8,7,6,5,4,3,2,1,0

What am I doing wrong here..?

Answer 1

Swift 4:

    var totalTime = 10
    var countdownTimer: Timer!

    @IBOutlet weak var timeLabel: UILabel!

    override func viewDidLoad() {
      super.viewDidLoad()
      startTimer()
    }

This method call initializes the timer. It specifies the timeInterval (how often the a method will be called) and the selector (the method being called).

The interval is measured seconds so for it to perform like a standard clock we should set this argument to 1.

    func startTimer() {
         countdownTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateTime), userInfo: nil, repeats: true)
    }

// Stops the timer from ever firing again and requests its removal from its run loop.
   func endTimer() {
       countdownTimer.invalidate()
   }

  //updateTimer is the name of the method that will be called at each second. This method will update the label
   @objc func updateTime() {
      timeLabel.text = "\(totalTime)"

       if totalTime != 0 {
          totalTime -= 1
       } else {
          endTimer()
       }
   }