How do you create an animation like the iBooks app's moving bookmark?

When you tap the bookmark, it slides down or up smoothly. As it slides up, it disappears as if behind the view directly above it. I know how to animate changing the frame of a view, but I don't know how to make it disappear like that. (I don't want to resize the UIImage, just slid开发者_运维问答e the UIImageView up and out of sight.)

I figure I need an invisible button to toggle the animation, and an UIImageView to animate. Do I need to change the bounds of the UIImageView, or should I use the frame? I thought I could just change the height from X to 0, but it didn't seem to resize the UIImageView. I had a little luck with settings the bounds with clipping subview's enabled, but I wasn't quite there.

I don't think I understand the relationship between the bounds and the frame.

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I ended up adding a parent UIView to contain the UIImageView. It has the dimensions in which I want the UIImageView to be viewable in, and then I just animate the frame so the Y dimension is equal to the negative height and it slides up nicely.

I was on the wrong track with the bounds.