NSTimer to to 4 digit label update - ios

Question

I just made a stopwatch with a tutorial but what I would like to do is to update my 00:00 label as 1 second increasing such as 00:01, 00:02: 00:03 and to do the same for minutes. Is there anyway of doing that? Thanks in advance!

Answer 1

Then you have to get the date which will start the counting from which is the current date when a particular event occurs, let's say we will start the timer when the view appears, so implement viewWillAppear as follows:
var currentDate = NSDate()
override func viewWillAppear(animated: Bool) {
currentDate = NSDate()
var timer: NSTimer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: "updateLabel", userInfo: nil, repeats: true)
timer.fire()
}
and implement the updateLabel function:
func updateLabel() {
dispatch_async(dispatch_get_main_queue(), { () -> Void in
var elapsedSeconds: NSTimeInterval = -self.currentDate.timeIntervalSinceNow
let minutes: Int = Int(elapsedSeconds)/60
let seconds: Int = Int(elapsedSeconds) - (minutes*60)
self.timeLabel.text = String(format: "%02d:%02d", minutes, seconds)
})
}

Answer 2

When formatting time elapsed, NSDateComponentsFormatter is another option:
var start: CFAbsoluteTime!
override func viewDidLoad() {
super.viewDidLoad()
start = CFAbsoluteTimeGetCurrent()
NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: "handleTimer:", userInfo: nil, repeats: true)
}
lazy var formatter: NSDateComponentsFormatter = {
let _formatter = NSDateComponentsFormatter()
_formatter.allowedUnits = .CalendarUnitMinute | .CalendarUnitSecond
_formatter.zeroFormattingBehavior = .Pad
return _formatter
}()
func handleTimer(timer: NSTimer) {
let elapsed = CFAbsoluteTimeGetCurrent() - start
label.text = formatter.stringFromTimeInterval(elapsed)
}
Admittedly, that will give you the time elapsed in 0:00 format, not 00:00 format.

Answer 3

This is Objective-C, but you'll get the idea:
-(void) updateTotalTime
{
int forHours = timeInSeconds / 3600,
remainder = timeInSeconds % 3600,
forMinutes = remainder / 60,
forSeconds = remainder % 60;
[elapsedTime setString:[NSString stringWithFormat:NSLocalizedString(#"elapsedTime", nil)
,forHours
,forMinutes
,forSeconds]];
}
and in my Localizable.strings:
"elapsedTime" = "Time: %02d:%02d:%02d";