Question

I want to start an NSTimer at viewdidload and then execute a few void functions at specific intervals. How do I do this?

Thanks!

Answer 1

Here’s your basic pattern:

MyViewController.h:

...
@interface MyViewController : UIViewController
{
    ...
    NSTimer* timer;
    ...
}
...

MyViewController.m:

...
static const NSTimeInterval TIMER_INTERVAL = 1.0;
...
- (void)dealloc
{
    [self stopTimer];
    ...
    [super dealloc];
}
...
- (void)viewDidLoad
{
    ...
    [self startTimer];
    ...
}
...
- (void)startTimer
{
    [self stopTimer];

    timer = [NSTimer scheduledTimerWithTimeInterval:TIMER_INTERVAL
                                             target:self
                                             selector:@selector(timerCallback)
                                             userInfo:nil
                                             repeats:YES];
    [timer retain];
}
...
- (void)stopTimer
{
    if (timer)
    {
        [timer invalidate];
        [timer release];
        timer = nil;
    }
}
...
- (void)timerCallback
{
    someFunction();
    [self someMethod];
}