NSTimer is not repeating as expected

Question

Possible Duplicate:
NSTimer timerWithTimeInterval: not working

In my app I have the following settings to run an action with a NSTimer:

in the m. file:

@implementation MYViewController {
      NSTimer *aTimer;
}

Than, when the user clicks the relevant button I have:

- (IBAction)userClick:(id)sender {
     aTimer = [NSTimer timerWithTimeInterval:1.0 
                                      target:self 
                                    selector:@selector(doSomethingWithTimer:) 
                                    userInfo:nil 
                                     repeats:YES]; 
     //[aTimer fire]; //NSTimer was fired just once.
}

and I also have:

-(void)doSomethingWithTimer:(NSTimer*)timer {
     NSLog(@"something to be done");
}

I would expect to have a line in the consul saying "something to be done" every one second. The timer is not called even once. I already tried firing the NSTimer using [aTimer fire] but it fires it just once and doesn't repeat as I expect.

Can anyone direct me to how to approach this?

please check my question http://stackoverflow.com/questions/11058571/nstimer-timerwithtimeinterval-not-working — Midhun MP, Jan 07 '13 at 12:43

score 9 · Accepted Answer · edited Sep 10 '14 at 12:30

9

Use

- (NSTimer *)scheduledTimerWithTimeInterval:target:selector:userInfo:repeats:

and then you won't have to add it to run loop manually.

edited Sep 10 '14 at 12:30

Alex Cio

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answered Jan 07 '13 at 12:32

Andy

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I thought that I did... have I used it wrongly (see example code in my original question)? – Ohad Regev Jan 07 '13 at 13:06
5

You used timerWithTimeInterval, not scheduledTimerWithTimeInterval – Andy Jan 07 '13 at 13:06

score 4 · Answer 2 · answered Jan 07 '13 at 12:29

4

You need to add the timer to a run loop:

[[NSRunLoop mainRunLoop] addTimer:aTimer forMode:NSDefaultRunLoopMode];

answered Jan 07 '13 at 12:29

Stavash

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I'm familiar with this option. When reading about it, I was not clear regarding to what I should do when I wish the NSTimer to stop working. Do you have any idea? – Ohad Regev Jan 07 '13 at 13:03
1

Calling invalidate on the timer instance should still do the trick – Stavash Jan 07 '13 at 13:06

score 1 · Answer 3 · edited Sep 10 '14 at 12:31

1

The problem here is scope. Your aTimer variable needs to be a field so it doesn't get GC'd once you leave the userClick method e.g.

NSTimer *timer;

...

- (IBAction)userClick:(id)sender {
    if (timer != nil && [timer isValid]) {
        [timer invalidate];
        timer = nil;
    }
    timer = [NSTimer scheduledTimerWithTimeInterval:1.0 
                                             target:self 
                                           selector:@selector(doSomethingWithTimer:) 
                                           userInfo:nil 
                                            repeats:YES]; 
}

edited Sep 10 '14 at 12:31

Alex Cio

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answered Jan 07 '13 at 12:29

James

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Where should the ---NSTimer *timer--- be defined? – Ohad Regev Jan 07 '13 at 13:02
It should be declared as a class field. – James Jan 07 '13 at 13:12

NSTimer is not repeating as expected

3 Answers3