On compiling my game made using Cocos2dx(c++) on Xcode 6.4, I can see various files which are generated with in DerivedData folder like :-
*.o files *.dia files *.d files.
I understand the first one as being object files what are the last two files ? I searched a lot but not able to find anything about them.
Edit: Checked in http://www.file-extensions.org/ also nothing there.