整理代碼，開頭定義此類需要用的方法

// By adding another @interface with the same name of the class but adding an identifier in brackets

// you can define private class methods. These are methods which are only used in this class and should

// not be used by other classes. Adding these method definitions gets rid of the "may not respond to selector"

// warning messages. The warning messages are not the problem, the problem is when the warning holds true

// and one of the selectors really can't respond. Typically due to a spelling mistake. In that case the App

// would simply crash. It's good practice to get rid of "may not respond to selector" warnings since they can

// be important indicators to potential crashes.

@interface GameScene (PrivateMethods)

-(void) initSpiders;

-(void) resetSpiders;

-(void) spidersUpdate:(ccTime)delta;

-(void) runSpiderMoveSequence:(CCSprite*)spider;

-(void) runSpiderWiggleSequence:(CCSprite*)spider;

-(void) spiderDidDrop:(id)sender;

-(void) checkForCollision;

-(void) showGameOver;

-(void) resetGame;

@end