From the View and Window Architecture Programming Guide for iOS:
A view object tracks its size and location using its frame, bounds,
and center properties:The frame property contains the frame rectangle, which specifies the
size and location of the view in its superview’s coordinate system.The bounds property contains the bounds rectangle, which specifies the
size of the view (and its content origin) in the view’s own local
coordinate system.The center property contains the known center point of the view in the
superview’s coordinate system.
Here is a good visualization of that explanation:
