How to make a UILabel that constantly updates in Objective-C

Question

I'm looking to make a UILabel display the current progress of a timer. Right now to get the current time left I call [timer1 timeLeft]; which returns an int. In this way I can update the label ONCE, at one instant. In what way can I update the label (mainLabel) constantly so that it is always displaying the current timer progress while being somewhat resource efficient?

Thanks for all your help!

Answer 1

Use following code for Countdown timer.

dblElapsedSeconds=0.0; //Declare this in header
tmrElapsedTime = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(updateElapsedTime) userInfo:nil repeats:YES]; //Declare timer variable in header

-(void)updateElapsedTime
{
    dblElapsedSeconds += 1;
    //double seconds = [[NSDate date] timeIntervalSinceDate:self.startTime];
    int hours,minutes, lseconds;
    hours = dblElapsedSeconds / 3600;
    minutes = (dblElapsedSeconds - (hours*3600)) / 60;
    lseconds = fmod(dblElapsedSeconds, 60); 
    [lblTimeElapsed setText:[NSString stringWithFormat:@"%02d:%02d",minutes, lseconds]];
}