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POTouch Event on image , achieved by using UIButton but show up delayed compare to UIImageView
 

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  1. POTouch Event on image , achieved by using UIButton but show up delayed compare to UIImageView
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    <p>Sorry for the messy title, I just don't know how to describe the problem in a delicate way.</p> <p>I'm writing a album-like app to display a bunch of image in my scrollview and do something when a image is touched.</p> <p>I followed this question : <a href="https://stackoverflow.com/q/855095/686011">how can i detect the touch event of an UIImageView</a> and use button with background image to handle touch event.</p> <p>My original method is using NSOperation to concurrently fetch image from internet and put it io a imageview and add to my scrollview, and the speed is quite ok because each imageview shows right after each NSOperation callback.</p> <p>Then I change imageview to uibutton, the strange thing is that when a NSOperation callback, that button does not show in my view. They show up at once when all the NSOperation callback is done. That makes the user experience become unacceptable.</p> <p>This is my NSOperation callback function, it will pass a button that contains the image fetched from internet</p> <pre><code>- (void)imageLoaded:(UIButton*)button; { NSLog(@"Done"); [button addTarget:self action:@selector(buttonPressed:) forControlEvents:UIControlEventTouchUpInside]; [self.view addSubview:button]; } </code></pre> <p>The buttons will only displa after the last "Done" appear instead of one by one, is that normal? or I messed up something?</p> <p>==== update ========</p> <p>I think I'm running the NSOperation on my viewcontroller. I have a imageLoadOperation class, I'll pass my viewcontroller to it</p> <pre><code>imageLoadOperation *ilo = [[imageLoadOperation alloc] initWithURLString:[NSString stringWithFormat:@"link for the image"]; [ilo setParent:self]; [queue addOperation:ilo]; [ilo release]; </code></pre> <p>And in the main function of imageLoadOperation I'll do </p> <pre><code>[parentViewController performSelectorOnMainThread:@selector(imageLoaded:) withObject:button waitUntilDone:NO]; </code></pre> <p>Do you mean I need to move these code to my AppDelegate instead of running in my viewcontrollor?</p>
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    1. USCommunity
    1. USTing-Chun Wang
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    1. COGuessing that you have to do such things in the main-thread -> maybe a method called from your imageLoaded by performSelectorOnMainThread
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      1. USTill
    2. COTill is right, you need to do this work from the main thread. UIImageView may have worked but that was just an implementation wrinkle.
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      1. USBen Stiglitz
    3. COThanks for the reply, I've update the code of my NSOperation, do you mean that I should move it to my AppDelegate instead of viewcontroller?
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      1. USTing-Chun Wang
 

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