{ Ellis Min }

[Swift]: Add Live Timer on Controller

swift

05/07/2019

Adding a live timer in Swift 5

1) Create a label

SWIFT
@IBOutlet weak var timeLapse: UILabel!

2) Make other instance variables

SWIFT
// Timer
var timer = Timer()
var seconds = 0

3) Create functions to start the timer

SWIFT
func startTimer() {
    // Time interval: frequency of method called. 1: every sec
    // selector: method being called
    timer = Timer.scheduledTimer(timeInterval: 1, target: self,   selector: (#selector(self.updateTimer)), userInfo: nil, repeats: true)
}


@objc
func updateTimer() {
    seconds += 1
    timeLapse.text = "\(seconds)"
}

Once startTime() is called, it will call updateTimer() every second

3) Call the implemented func from a button to start to timer:

SWIFT
@IBAction func restartGame() {
    // Reset the timer
    timer.invalidate()
    seconds = 0
    timeLapse.text = formatTime(time: TimeInterval(seconds))


    startTimer()


}

Since the Concentration game needs a restart on a new game button or after fininshing a game, it needs to invalidate() the timer. Otherwise, there will be a multiple timers running at the same time, increasing multiple seconds per second.

4) Format time

So far, the timeLapse label only has a text that increases from initial seconds = 0 to seconds += 1 per second. It needs a formatting

SWIFT
func formatTime(time: TimeInterval) -> String {
    let minutes = Int(time) / 60 % 60
    let seconds = Int(time) % 60
    return String(format:"%02i:%02i", minutes, seconds)
}

Now, back to 3) to update the formated time. Change

SWIFT
@objc
func updateTimer() {
    seconds += 1
    timeLapse.text = "\(seconds)"
}

to

SWIFT
@objc
func updateTimer() {
    seconds += 1
    timeLapse.text = formatTime(time: TimeInterval(seconds))
}

WRITTEN BY

Ellis Min

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