ios - Way to tell if view is currently displaying on users screen?

Question

I've got this animation that I'd like to run but I only want the animation to run when a user has scrolled down and the item that is in the scrollview is now visible on the users screen. Is there a way to check if a view is currently visible on the users screen to then enable this animation to run? Thank you in advance!

Answer 1

One thing you could do is the following:

First, get the currently visible area of your scroll view. That is going to be the scroll view's bound plus the contentOffset.

Second, use the CGRectContainsRect() function to determine if your view's frame is inside the visible area.

Here is some example code:

CGRect visibleRect;
visibleRect.size = myScrollView.bounds.size;
visibleRect.origin = myScrollView.contentOffset;

CGRect containedViewRect = myView.bounds;

if ( CGRectContainsRect( visibleRect, containedViewRect) && !myView.hidden ) 
{
    // The view is visible!
}

Hope this helps!