How Do I create a countdown timer with minutes and seconds in swift?

Question

I can't find a single tutorial that does countdown timer with minutes and seconds. There's one or two but they are kind of bad.

import UIKit

class HomeViewController: UIViewController {
    @IBOutlet weak var focusSession: UILabel!
    @IBOutlet weak var breakSession: UILabel!

    var prodSeconds = String() // This value is set in a different view controller
    lazy var intProdSeconds = Int(prodSeconds)
    var timer = Timer()
    var isTimerRunning = false  // Make sure only one timer is running at a time

    override func viewDidLoad() {
        super.viewDidLoad()

        if isTimerRunning == false {
            runProdTimer()
        }

        //focusSession.text = String(prodMinutes) + ":" + String(prodSeconds) // Ignore this for now stack overflow ppl
    }

    func runProdTimer() {
        timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: (#selector(HomeViewController.updateProdTimer)), userInfo: nil, repeats: true)
        isTimerRunning = true
    }

    @objc func updateProdTimer() {
        if intProdSeconds! < 1 {
            timer.invalidate()
            focusSession.text = "00:00"
        }
        else {
            intProdSeconds! -= 1
            focusSession.text = prodTimeString(time: TimeInterval(prodSeconds)!)
        }
    }

    func prodTimeString(time: TimeInterval) -> String {
        let prodMinutes = Int(time) / 60 % 60
        let prodSeconds = Int(time) % 60

        return String(format: "%02d:%02d", prodMinutes, prodSeconds)
    }
}

The user inputs their time amount and it is stored in the prodSeconds variable which is then converted to an Int below it with the lazy variable.

However, the timer still doesn't countdown when I run the app. This is supposedly just a timer for seconds which I was following from a different tutorial. But all that happens is that the label that displays the timer simply displays the number inputted by the user in the format of 00:prodSeconds and doesn't actually countdown.

P.S. Don't worry about implementing a start/stop button for now. In my case, the timer is supposed to start when the view loads.

Your question is unclear. Your `prodTimeString` function works just fine. Pass in `90` and you get `01:30`. — rmaddy, Jul 04 '18 at 19:02
You might want to avoid simply subtracting 1 every second; `Timer` is not very accuracte. I would suggest you calculate the `Date` that corresponds to your end time and then use `timeIntervalSinceNow` to calculate the remaining time. Also, run your timer at less than a second, say 0.5s, in order to avoid jitter in your countdown — Paulw11, Jul 04 '18 at 21:28
@rmaddy Ok, I see that now...but the thing is, the user will be inputting minutes not seconds...right now, whatever input that goes in is read as seconds not minutes...how would I have it so that the minutes inputted by the user is taken in as minutes and then converted to seconds? — YungGoat, Jul 05 '18 at 01:01

score 3 · Accepted Answer · answered Jul 04 '18 at 19:18

3

The problem is that you count down from

intProdSeconds! -= 1

and pass prodSeconds to this

focusSession.text = prodTimeString(time: TimeInterval(prodSeconds)!)

so make sure to deal only with intProdSeconds

answered Jul 04 '18 at 19:18

Shehata Gamal

98,760
8
65
87

How Do I create a countdown timer with minutes and seconds in swift?

1 Answers1