Scrollview thread timer iphone

Question

Possible Duplicate:
UIScrollView pauses NSTimer until scrolling finishes

I have a scrollview and a label to show the countdown to date. I got the countdown working but whenever I drag the scrollview up and down the countdown stopped but when I release my finger it started working again. I know it has to do with muti-threading. Here is my code

-(void) viewdidload
{
    timer = [NSTimer scheduledTimerWithTimeInterval:0 target:self selector:@selector(updateLabel) userInfo:nil repeats:YES];
}

-(void)updateLabel {


    NSCalendar *calender = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDateComponents *countdown = [calender  
                                   components:(NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) 
                                   fromDate:[NSDate date] 
                                   toDate:destDate 
                                   options:0];

    timerCountDown.text = [NSString stringWithFormat:@"%dday %dh %dm %ds", [countdown day],[countdown hour],[countdown minute],[countdown second]];
}

score 1 · Answer 1 · answered Aug 01 '11 at 05:17

Instead of going through all the trouble of adding a thread or what not, make this simple:

On finger down / touchesBegan. Record or save the current time in milliseconds (A)
On finger up / touchesEnded(?) Record or save the current time again (B)
Minus A from B to have the missed/paused time in milliseconds which you then subtract from the timer's time.

Only problem with this is, the clock on the screen will pause while scrolling but as soon as you release it will update or refresh again.

Hope this solves your problem in a way simpler than threads manner. LH

Ilanchezhian · Accepted Answer · 2011-08-01T05:58:42.450

0

You set the text to the UILabel by the following way.

NSString *cntTime = [NSString stringWithFormat:@"%dday %dh %dm %ds", [countdown day],[countdown hour],[countdown minute],[countdown second]];
[timerCountDown performSelectorOnMainThread:@selector(setText:) withObject:cntTime waitUntilDone:YES];

Edit:

The method should be -(void)viewDidLoad.

Also , give some time interval, say 1 sec,

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

And, are u implementing any UIScrollViewDelegate methods?

edited Aug 01 '11 at 05:58

answered Aug 01 '11 at 05:01

Ilanchezhian

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I tried, but it didn't work :( – kevin Aug 01 '11 at 05:52
I didn't implement any scrollviewdelegate – kevin Aug 01 '11 at 09:39
I thought the problem is that the `updateLabel` is not called during scrolling? – DanSkeel May 27 '12 at 10:47

score 0 · Answer 3 · answered Aug 01 '11 at 05:20

Nideo's answer is good (as long as you are proceeding in a strict countdown and you can predict what the value of the thing you are displaying will be). However you could find yourself needing to display a count of events that are happening at random. If so you could implement the scrollview delegate method scrollViewDidScroll: and refresh the data from its source (i.e. call updateLabel). You could also subclass UIScrollView and implement touchesBegan:/touchesMoved:/touchesEnded:, refreshing the displayed value in each, then passing the event up to super to allow normal touch handling.

Scrollview thread timer iphone

3 Answers3