How to Show the time for an event in ios - ios

Question

In my iOS app I have to create a Digital timer (Not the system Time) in the HH:MM:SS format which should start from 00:00:00 on tap of a button, can I make use of any standard library to do so? Or I should write my own logic?

Answer 1

So one thing you can do is to create a timer and remember time in which you created it.
#IBAction func buttonTapped() {
// Store date / time in which you tapped the button
self.initialDate = NSDate()
// Create timer that fires every second starting now (scheduled), and repeats
self.timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("timerTick"), userInfo: nil, repeats: true)
}
Then, when you have initial stuff, you can do timerTick method. In here, you get current date, do difference between your stored one and current and present it:
func timerTick() {
// Get calendar and components of the dates in interval <initialDate, currentDate>
let calendar = NSCalendar.currentCalendar()
let components = calendar.components(.CalendarUnitSecond | .CalendarUnitMinute | .CalendarUnitHour, fromDate: self.initialDate, toDate: NSDate(), options: NSCalendarOptions.allZeros)
// In this point you have minutes, seconds and hours, you can just present it
// "%02d:%02d:%02d" in format means "number, always at least 2 numbers, fill with zeroes if needed")
self.label.text = String(format: "%02d:%02d:%02d", components.hour, components.minute, components.second)
}
If you want to stop the timer, you can do it by calling self.timer.invalidate()
Hope it helps!

Answer 2

The iOS Foundation framework includes the NSDateFormatter class (and the NSDate data type) which does just this.

Answer 3

In your .m file add these properties:
#import "MyVC.h"
#interface MyVC()
#property (strong, nonatomic) NSTimer* timer; // our timer
#property (nonatomic) NSInteger secondsPassed; // how many seconds have been passed since the start of the timer
#end
In viewDidLoad or in the IBAction method of your UIButton:
- (void)viewDidLoad {
[super viewDidLoad];
self.myLabel.text = #"00:00:00"; // start text
// invoke updateTimer every second
self.timer = [NSTimer scheduledTimerWithTimeInterval: 1.0
target:self
selector:#selector(updateTimer)
userInfo:nil
repeats: YES];
}
This method will be called every second to update the UILabel
-(void) updateTimer{
NSInteger hours, minutes, seconds;
// increase the passed seconds
self.secondsPassed++;
// calculate the hours, minutes, seconds from the total number of seconds
hours = self.secondsPassed / 3600;
minutes = ( self.secondsPassed % 3600) / 60;
seconds = ( self.secondsPassed %3600) % 60;
// update the label with the time
self.myLabel.text = [NSString stringWithFormat:#"%02zd:%02zd:%02zd", hours, minutes, seconds];
}
alternatively you can use MZTimerLabel