Stop pinwheel of death in infinite loop Objective C

Question

I am writing a simple timer program for myself in objective c for my mac. The timer counts down properly, but I get the spinning pinwheel of death. How can I make the pinwheel go away? I think its because I have an infinite loop but there must be someway to bypass it.

I have an IBAction that triggered on a button click (the button is start). And from there, it calls another function that does the work.

Here is my IBAction:

- (IBAction)timerStart:(id)sender {
    self.timerDidPause = NO;
    [self timerRunning];
}

And here is timerRunning:

- (void)timerRunning {
for (;;) {
    usleep(1000000);
    if (self.timerDidPause == YES) {

    }
    else {
        if (self.seconds == 0) {
            if (self.minutes == 0) {
                [self timerDone];
                break;
            }
            else {
                self.seconds = 59;
                self.minutes = self.minutes - 1;
                [self formatTimerLabel:self.hours :self.minutes :self.seconds];
            }
        }
        else {
            self.seconds = self.seconds - 1;
            [self formatTimerLabel:self.hours :self.minutes :self.seconds];
        }
    }
}
}

In this function, the function formatTimerLabel is called so here is that:

- (void)formatTimerLabel:(int)hours
                    :(int)minutes
                    :(int)seconds {
NSString *minuteString = [[NSString alloc] init];
NSString *secondString = [[NSString alloc] init];
if (minutes < 10) {
    minuteString = [NSString stringWithFormat:@"0%d", minutes];
}
else {
    minuteString = [NSString stringWithFormat:@"%d", minutes];
}
if (seconds < 10) {
    secondString = [NSString stringWithFormat:@"0%d", seconds];
}
else {
    secondString = [NSString stringWithFormat:@"%d", seconds];
}
[self.timerLabel setStringValue:[NSString stringWithFormat:@"%d:%@:%@", hours, minuteString, secondString]];
[self.timerLabel display];
}

Answer 1

You're causing the UI thread to hang with your loop. After a couple of seconds of that, the OS switches the cursor to a pinwheel.

You need to look into NSTimer and the Timer Programming Guide to schedule the timer to run outside of the UI thread.