scheduledTimerWithTimeInterval not updating timer method while scrolling?

Question

I have strange issue with timer. timer is updating well within application. i am showing the code.

// Start Timer

#pragma mark- Timer
- (void)startTimer
{
    timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateTimer:) userInfo:nil repeats:YES];
}

// Update Timer

- (void)updateTimer:(NSTimer *)theTimer
{
    NSLog(@"called"); 
}

Problem: I have a textview when i scroll text within the textview the updateTimer method stops calling and when I stop scrolling then it starts to update timer.

Now what to do to continue calling the update timer method?

ButtonClick there is no issue with that. only one time called — Sunny Shah, May 29 '14 at 05:17
this is duplicate of http://stackoverflow.com/questions/7059366/uiscrollview-pauses-nstimer-while-scrolling — Banker Mittal, May 29 '14 at 05:25

score 5 · Accepted Answer · answered May 29 '14 at 05:15

5

For do fix this issue you need to add your NSTimer to the mainRunLoop. Such like,

- (void)startTimer
{
    timer = [NSTimer scheduledTimerWithTimeInterval:1.0f target:self selector:@selector(updateTimer:) userInfo:nil repeats:YES];
    [[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
}

answered May 29 '14 at 05:15

iPatel

46,010
16
115
137

1

If you're going to add the timer to the runloop manually (which you need to to fix this problem), you should use timerWithTimeInterval:target:selector:userInfo:repeats:, instead of scheduledTimer... – rdelmar May 29 '14 at 05:22
@iPatel can u explain this answer in simple words why need to use – Sunny Shah May 29 '14 at 05:28
@SunnyShah - http://stackoverflow.com/questions/9918103/nstimer-requiring-me-to-add-it-to-a-runloop – iPatel May 29 '14 at 05:31
I think while a UIScrollView (or a derived class thereof) is scrolling, it seems like all the NSTimers that are running get paused until the scroll is finished thats why this happens. – Banker Mittal May 29 '14 at 05:54
@rdelmar - Thanks, can you explain me why `timerWithTimeInterval:target:selector:userInfo:repeats` is better for us when we are use of `NSRunLoop`. – iPatel May 29 '14 at 05:56
@rdelmar please add the full answer above line is not working – Sunny Shah May 29 '14 at 06:01
@iPatel, because scheduledTimer automatically adds the timer to the runloop in the default mode. You then add it to the runloop in common mode. I don't know whether that adds it twice or not, but the only reason to use the scheduledTimer version is to get the automatic adding to the runloop -- if its adding it in the wrong mode for your use, why use it? – rdelmar May 29 '14 at 06:01

score 0 · Answer 2 · answered May 29 '14 at 05:50

0

You can do this way also,

 NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.001 
                                                             target:self 
                                                           selector:@selector(updateTimer:) 
                                                           userInfo:nil 
                                                            repeats:YES];
[[NSRunLoop currentRunLoop] addTimer:timer 
                             forMode:NSRunLoopCommonModes];

answered May 29 '14 at 05:50

Banker Mittal

1,918
14
26

whats the difference between your and @iPatel answer – Sunny Shah May 29 '14 at 05:58
currentRunLoop returns the NSRunLoop object for the current thread. mainRunLoop returns the run loop of the main thread. – Banker Mittal May 29 '14 at 06:03
1

thats not clear for me. what's the best to use NSRunLoop or currentRunLoop. please explain in some words. – Sunny Shah May 29 '14 at 06:07

scheduledTimerWithTimeInterval not updating timer method while scrolling?

2 Answers2