按下返回键监听

function FightScene:onKeyboard(code,event)
    if code == cc.KeyCode.KEY_BACK then
        print("按下返回键")
        GameApp:enterScene("MainScene");
    end
end

function FightScene:onEnter()
    self.keyListener = cc.EventListenerKeyboard:create()
    --handler(self,self.onKeyboard)用来关联方法，如果方法直接放在当前位置则可以直接使用无需handler
    self.keyListener:registerScriptHandler(handler(self,self.onKeyboard),cc.Handler.EVENT_KEYBOARD_RELEASED)
    local eventDispatch = self:getEventDispatcher()
    eventDispatch:addEventListenerWithSceneGraPHPriority(self.keyListener,self)
end