Hello Guys..
I see, I have been using GCD and blocks but on somme OSX app I did before, not
on iPhone, I tough tit wasn't there... :P.
SO, I from within the method( block) that makes all the saving process, I do
something like
>> dispatch_async(dispatch_get_main_queue(), ^{
>> // code executed on main thread goes here (i.e., updating the
>> progress indicator in your case
>>
>> });
and update the progress indicator bar, great im gonna try that..
also I have the option to call from within the same method a [<MyConotroller
With the Progress indicator> performSelectorinMainThread: withObject:<NSNumber
with the float value to add> waitUntilDone:NO];
right?
What about the saving operation improving its saving time?, I will check today
what takes longer, if creating the thumbnial, or encoding the views, maybe I
shouldn't encode the whole view, but s just the image reference and the
transform matrix... ?/ I will try that one also.
Thanks for the replies..
Gustavo
On Dec 7, 2010, at 4:22 AM, [email protected] wrote:
>
> On Dec 6, 2010, at 9:21 PM, Laurent Daudelin wrote:
>
>> On Dec 6, 2010, at 17:16, [email protected] wrote:
>>
>>> On Dec 6, 2010, at 5:37 PM, Gustavo Pizano wrote:
>>>
>>>> Hello.
>>>>
>>>> My application is saving some data, and it takes a while to do it, it can
>>>> be 1 second to 10 sec around.. Im doing some image processing, The thing
>>>> is..
>>>>
>>>> I send the saving operation in another thread using the NSThread +
>>>> detachNewThreadSelector:toTarget:withObject: method, and in the main
>>>> thread I update a UIActivityIndicator, and stop it when I receive the
>>>> NSThreadWillExitNotification. The problem is that when it takes long to
>>>> save, it may seem the app is somehow stuck, even the spinning indicator is
>>>> running. I wanted to change the ActivityIndicator to a progressview, but
>>>> then I can't make it work because the saving process not on the main
>>>> thread, i think.. correct me if Im wrong, Im not so much familiar with
>>>> multithreaded apps.
>>>>
>>>> As for the saving process, what I do is the following.
>>>>
>>>> I have a Parent view which contains subviews, these subviews are drawing
>>>> images. The user can modify this images, (scale and rotate), so when I
>>>> save i encode these views so it will save the view's transform, and then
>>>> I archive the data I encoded for all these subviews.
>>>
>>>
>>> <your code deleted>
>>>
>>> You are correct that you cannot call GUI methods from other threads, but
>>> NSObject (which all your UI objects inherit from) has the method.
>>>
>>> - (void)performSelectorInBackground:(SEL)aSelector withObject:(id)arg
>>>
>>> So from your other thread, you can update the progress indicator by using
>>> it to call a method that updates the progress.
>>>
>>>
>>> This is even easier if you are targeting iOS 4.0 and higher using Blocks
>>> and GrandCentral Dispatch.
>>>
>>> Code typed in email (i.e., not tested):
>>>
>>> dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT,
>>> 0), ^{
>>> // code you want implemented on another thread goes here:
>>>
>>> dispatch_async(dispatch_get_main_queue(), ^{
>>> // code executed on main thread goes here (i.e., updating the
>>> progress indicator in your case
>>>
>>> });
>>> });
>>>
>>> HTH,
>>> Dave
>>
>> Maybe I'm missing something but aren't the UI actions supposed to happen in
>> the main thread, in this case, he should really call
>> "performSelectorOnMainThread:withObject:waitUntilDone:"?
>>
>> -Laurent.
>
>
> I copied and pasted the wrong method. Yes, the onMainThread version is the
> one to use for this.
>
> The Grand Central Dispatch code is ok though as Conrad pointed out.
>
> Dave
>
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