Re: UIActivityIndicatorView
Re: UIActivityIndicatorView
- Subject: Re: UIActivityIndicatorView
- From: Luca Ciciriello <email@hidden>
- Date: Tue, 15 Jan 2013 16:38:42 +0100
Understood, thanks.
Luca.
On Jan 15, 2013, at 4:31 PM, Uli Kusterer <email@hidden> wrote:
> On Jan 15, 2013, at 3:18 PM, Luca Ciciriello <email@hidden> wrote:
>> I use an activity indicator in order to show, in my UIViewController, a "work in progress" activity.
>>
>> here my code
>>
>> - (void)myMethod
>> {
>> [[self activityElab] setHidden:NO];
>> [[self activityElab] startAnimating];
>>
>> // here I call a very CPU-intensive method.
>>
>> [[self activityElab] setHidden:YES];
>> [[self activityElab] stopAnimating];
>> }
>>
>> My problem is that nothing appear (activity indicator) when myMethod is called. Now if I remove (comment) the call to my "intensive activity" method all is working fine.
>>
>> Any idea? I've tested this code both on the simulator and on a device (iPad) with iOS 5.0 and iOS 6.0
>> My environment is Xcode 4.5.2 on OS X 10.8.2.
>
>
> That won't work. Views are only redrawn once your method returns. So while your activity indicator is shown and hidden, nobody will ever see it. If you do activities that take a long time, you'd better split them up into smaller NSOperations which let the main thread redraw the UI in between each operation. Or if you have to, use a separate thread, but that's hard to get right, and easy to get wrong in a way that causes random hard-to-find crashes.
>
> Cheers,
> -- Uli Kusterer
> "The Witnesses of TeachText are everywhere..."
> http://www.zathras.de
>
>
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