UIScrollView - detect image is in the middle of the screen

I am cre开发者_如何学运维ating an iPhone application and I have a UIScrollView. I'd like to ask how to detect that the imageview is in the middle of the page to display its label below the UIscrollview.

Thanks!

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hmm, you'd have to make your class conform to the UIScrollViewDelegate then use:

– scrollViewWillBeginDragging: to set an NSTimer to run a method which will check if myImage.center == myScrollView.center and then use – scrollViewDidEndDecelerating: to stop the timer.

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When you are scrolling your scroll view, a method of UIScrollViewDelegate will be called repeatedly during scrolling.

- (void)scrollViewDidScroll:(UIScrollView *)scrollView;

You can get the current context offset by scrollView's property.

- scrollViewWillBeginDragging and -scrollViewDidEndDecelerating won't be called, if you scroll the view by commands, which are in the UIScrollView class.