receiver type *** for instance message is a forward declaration

Question

In my iOS5 app, I have NSObject States class, and trying to init it:

states = [states init];

here is init

Answer 1

I got this sort of message when I had two files that depended on each other. The tricky thing here is that you'll get a circular reference if you just try to import each other (class A imports class B, class B imports class A) from their header files. So what you would do is instead place a forward (@class A) declaration in one of the classes' (class B's) header file. However, when attempting to use an ivar of class A within the implementation of class B, this very error comes up, merely adding an #import "A.h" in the .m file of class B fixed the problem for me.