Example of circular references using import statements

[jdemori]

I'm not sure I would call it circular references but from reading certain posts they use that notion. Attached is an archive which includes sample code of the issue I came across and the corrected version I got to work.

What I found...
http://forums.macnn.com/79/developer-center/144563/cannot-find-interface-declaration/


Again my approach was that imports prevented a file from being imported but never though that it had the potential of blocking other imports... At least thats what I got from it.
So what I would like to see is a better understanding of why and how to prevent that. Thanks.