Stop pinwheel of death in infinite loop Objective C - 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.