“Attempting to use the forward class 'Game' as superclass of 'MathGame'” in Cocos2d

Question

I\'m making a Cocos2d game for iphone, and I have my main game mode, Game, which inherits from CCLayer.

I\'m trying to make another game mo

Answer 1

You simply have an import cycle:

1. Game imports SplashScreenLayer
2. SplashScreenLayer imports MathGame
3. MathGame imports Game

Your solution:

Leave the import inside the MathGame, and change the other imports to @class.

To sum it up:

// Game.h
#import "cocos2d.h"
#import <GameKit/GameKit.h>

@class SplashScreenLayer;
@interface Game : CCLayer
    // A bunch of stuff
@end

The new game type:

// MathGame.h
#import "Game.h"

@interface MathGame : Game
@end

And the main menu that includes both:

// SplashScreen.h
#import "cocos2d.h"
#import "HowToPlayLayer.h"
#import "AboutLayer.h"

@class Game;
@class MathGame;
@interface SplashScreenLayer : CCLayer
    // A bunch of stuff
@end

---

With your question answered above, let me explain a few things I already know from reading about forward declerations and import cycles:

First, go read about them! They are a very important part of Objective-C, and you don't want to miss it!

Secondly, use @class whenever you need that class for private variables or method parameters. Use imports for inheritance and strong properties.

Thirdly, don't forget to #import your forwarded classes in the implementation file!

Answer 2

In my case,I user the xx class and use the @class but not #import the .h file.and the compile complain..