Expected specifier-qualifier-list before - list

Question

I have the following Objective-C headers:
// Menu.h
#import <UIKit/UIKit.h>
#import "GameController.h"
#interface Menu : UIImageView {
GameController *gameController; // "Expected specifier-qualifier-list
// before GameController"
}
- (void)appear;
#end
and
// GameController.h
#import <UIKit/UIKit.h>
#import "Menu.h"
#interface GameController : UIView {
Menu *menu; // "Unknown type name 'Menu'"
}
- (void)startLevel0;
- (void)startLevel1;
- (void)startLevel2;
#end
When I try to build the project, Xcode (v4) yells at me, saying Expected specifier-qualifier-list before GameController and unknown type name 'Menu'. I'm sure that they are somehow related, but I have no idea how?

Answer 1

It's not good practice to have mutually-including header files. Instead of importing Menu.h, use the #class directive. Try removing #import "Menu.h" and adding #class Menu in its place. Ditto for Menu.h (remove GameController include, and add the #class directive)

Answer 2

You have a circular reference in your imports. The compiler builds a dependency tree from the import statements so when two Classes rely on each other it doesn't know how to compile one before the other.
Sadly, gcc kicks out a fairly nonsensical error statement when this happens "Expected specifier-qualifier-list". #yan is correct that you should use the #class directive. Check out this question for a solid explanation: #class vs. #import