Question

Is it possible to make a UIView only appear inside a limited area of the screen, especially while animating? (When it reaches the boundary, it should simply cut off at the boundary point, as if it were being obscured by an object in front of it.) I need this because I have a roll-out menu comprised of UIButtons, and I don’t want the menu to extend beyond the edge of the toolbar when closed. Thank you!

(Alternatively, hiding the entire UIView upon reaching the boundary would also be acceptable. I just don’t know how to check for this condition without continuously querying the center property.)

Answer 1

You can define a clipping area for your UIVIew using the clipsToBounds property. If you are using CoreAnimation to animate your view, you may want to have a look a the maskToBounds property of CALayer objects as well (each UIVIew has a layer property of type CALayer).

From the UIView Class reference:

Normally, a subview’s visible area is
not clipped to the bounds of its
superview, but in iOS you can use the
clipsToBounds property to alter that
behavior.