NSTimer in background

Question

I am very new in Iphone Development. I have an issue . I am using a NSTimer which update a UiLabel in every second. now i have two problem :

when my app goes in background and after it when i open app . app goes hangs.
if i goes next or back on other ui screen then wen i comes on timer screen then my label again shows 0.

can anyone help me.

code which i am using :

timer = [NSTimer scheduledTimerWithTimeInterval: 1.0 target:self selector:@selector(updateCountdown) userInfo:nil repeats: YES];

-(void) updateCountdown
{
    secondsLeft--;

    //nits testing
    if(secondsLeft == 1)
    {
         [self.view addSubview:recipePage6View.view];
    }



    if (secondsLeft<0)
    {
        [timer invalidate];
        timer=nil;
        lblDisplayTimer.text =@"00:00:00";

    }
    else
    {
        hours = secondsLeft / 3600;
        minutes = (secondsLeft % 3600) / 60;
        seconds = (secondsLeft %3600) % 60;

        lblDisplayTimer.text = [NSString stringWithFormat:@"%02d:%02d:%02d", hours, minutes, seconds];
         //lblDisplayTimer.text = [NSString stringWithFormat:@"%02d:%02d",minutes,seconds];
     } 
}

All `NSTimer` are invalidated when your app enters the background. — rckoenes, Aug 08 '13 at 10:55
Cf. http://stackoverflow.com/questions/17414344/accuracy-of-nstimer/17414593#17414593 — nielsbot, Aug 08 '13 at 11:08

score 4 · Answer 1 · answered Aug 08 '13 at 10:57

4

You need to set up a special background timer task and not have an NSTimer on the main run loop which gets suspended in background. The documentation on how to do this is here

answered Aug 08 '13 at 10:57

David Elliman

1,379
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NSTimer in background

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