cocos2dx 3.3 quick lua 实现返回键退出程序

<span style="font-size:18px;">    local layer = display.newLayer()
self:addChild(layer,-10)
layer:setKeypadEnabled(true)
layer:addNodeEventListener(cc.KEYPAD_EVENT, function (event)
if event.key == "back" then  --返回键
print("back")  --弹出一个对话框，点击yes退出程序
device.showAlert("Confirm Exit", "Are you sure exit game ?", {"YES", "NO"}, function (event)

if event.buttonIndex == 1 then
cc.Director:getInstance():endToLua()
else
device.cancelAlert()  --取消对话框
end
end)
elseif event.key == "menu" then  --菜单键
print("menu")
end
end) </span>