UIButton fails to properly register touch in bottom region of iPhone screen

Question

I have an app with many different buttons arranged in a calculator like, square / rectangular format. It is actually extremely similar to the default iOS calculator. There a

Answer 1

I've prepared this answer in the hopes that someone else might find it helpful.

My problem was a little more difficult to discover the cause, but way easier to resolve. The button in question was in a custom sideBarView and XIB with four other buttons that I had programmatically initialized and loaded into the viewController. The top four worked fine. Only the bottom didn't seem to work...

CAUSE: The CGRect defined programmatically for the custom sideBarView was actually smaller in height than the XIB needed. However, since the sideBarView wasn't clipToBounds, it showed it the lowest button, but any taps on it were registered as taps on the view below and not as taps on the lowest button.

To discover this, I checked the 3D viewer, the order of the objects in the XIB and even took comparison snaps of each of the buttons in the simulator with Color-blended layers selected and with breakpoints on didTap... it wasn't until I shortened the spaces between the constraints between each button and discovered that nothing but only the top of the lowest button would accept the tap, which gave me the clue that it was height limitation somewhere (like the initialization code).