quick-cocos2d-x3.2 scheduler使用注意事项

最近在使用scheduler时发现如下问题

调用：

local scheduler = require(cc.PACKAGE_NAME .. ".scheduler")

function MainScene:ctor()

    self.player_:pos(self.player_:getContentSize().width / 2 , display.height / 2)

    scheduler.scheduleGlobal(self.addMonster,1)

end

function MainScene:addMonster()

    local monster = display.newSprite("monster.png"):addTo(self)
end

报错：

stack traceback:
	[string "framework/shortcodes.lua"]:62: in function 'addTo'
	[string "/Users/tokou/Documents/work_cocos/firstapp/src/app/scenes/MainScene.lua"]:30: in function <[string "/Users/tokou/Documents/work_cocos/firstapp/src/app/scenes/MainScene.lua"]:28>
cocos2d: ----------------------------------------

解决方法

local scheduler = require(cc.PACKAGE_NAME .. ".scheduler")

function MainScene:ctor()

    self.player_:pos(self.player_:getContentSize().width / 2 , display.height / 2)

   scheduler.scheduleGlobal(function()
        self:addMonster()
    end,1)

end

function MainScene:addMonster()

    local monster = display.newSprite("monster.png"):addTo(self)
end