我想让一个SKSpritenode只在一个方向上展开，在本例中是向上展开。overridefuncdidMoveToView(view:SKView){varrightlegs=SKSpriteNode()rightlegs.size=CGSize(width:10,height:50)rightlegs.color=SKColor.yellowColor()rightlegs.position=CGPointMake(self.frame.width/2+20,self.frame.height/2-40)self.addChild(rightlegs)}overridefuncto