Xcode duplicate symbol error

Question

I am getting \"Apple Mach-O Linker (Id) Error\":

ld: duplicate symbol _matrixIdentity in /BlahBlah/Corridor.o and /Blahblah/Drawable.o for architecture i386
         


        

Answer 1

From your description, utils.h declares and implements a variable, the implementation of which is compiled in corridor.h and Drawable.h by virtue of utils.h being included in both (indirectly through Drawable.h in the case of Corridor.h). Thus both compilation units contain an implementation for _matrixIdentity, and the linker complains.

Move the implementation of _matrixIdentity into a new module utils.m to ensure there is only one definition of the symbol.