Q:

'Illegal Geometry' warnings in Interface Builder... significant?

The 'info' button in Interface Builder shows me that there are dozens of 'Illegal Geometry' warnings, each one with the issue 'This view overlaps one of it's siblings.' Is this anything to be worried about? Will it stop the app being accepted by Apple? The errors are happening because I'm layering PNGs over each other when I make the interface.

A:

It should be fine. I have an app with the same warnings that was accepted with no problems.  
The issue is that overlapping siblings are not allowed if the views are not backed by Core Animation layers (default on the desktop). On the iPhone, all UIViews are backed by CoreAnimation layers, so the overlapping is acceptable. As stated in the documentation for UIViews (2nd paragraph, last sentence): "Sibling views are able to overlap without any issues, allowing complex view placement."

