场景(Scene)以及所有节点(Node)的生命周期事件如下:
enter。进入场景时候触发。
enterTransitionFinish。进入场景而且过渡动画结束时候触发。
exit。退出场景时候触发 。
exitTransitionDidStart。退出场景而且开始过渡动画时候触发。
cleanup。场景对象被清除时候触发。
提示 GameScene场景中的(Scene)继承于节点(Node),这些生命周期事件根本上是从Node继承而来。事实上所有Node对象(包括:场景、层、精灵等)都有这些事件,具体实现代码与GameScene场景类似。
我们为GameScene场景添加生命周期函数相关代码如下:require Cocos2d
require Cocos2dConstants
local SettingScene = require(SettingScene)
local size = cc.Director:getInstance():getWinSize()
local GameScene = class(GameScene,function()
return cc.Scene:create()
end)
function GameScene.create()
local scene = GameScene.new()
scene:addChild(scene:createLayer())
return scene
end
function GameScene:ctor()①
cclog(GameScene init)
--场景生命周期事件处理
local function onNodeEvent(event)
if event == enter then②
self:onEnter()
elseif event == enterTransitionFinish then③
self:onEnterTransitionFinish()
elseif event == exit then④
self:onExit()
elseif event == exitTransitionStart then⑤
self:onExitTransitionStart()
elseif event == cleanup then⑥
self:cleanup()
end
end
self:registerScriptHandler(onNodeEvent)⑦
end
function GameScene:onEnter()⑧
cclog(GameScene onEnter)
end
function GameScene:onEnterTransitionFinish()⑨
cclog(GameScene onEnterTransitionFinish)
end
function GameScene:onExit()⑩
cclog(GameScene onExit)
end
function GameScene:onExitTransitionStart()?
cclog(GameScene onExitTransitionStart)
end
function GameScene:cleanup()?
cclog(GameScene cleanup)
end
… …
return GameScene
上述代码第①行GameScene:ctor()是GameScene场景构造函数,在次函数中进行GameScene场景的初始化,也就是触发init事件。第②~⑥行代码场景生命周期事件处理,根据事件event对象判断是哪一种类型的场景生命周期事件。其中第②行是判断enter事件,是场景进入时候触发,判断为true情况下,然后通过代码self:onEnter()调用第⑧行的GameScene:onEnter()函数。
第③行是判断enterTransitionFinish事件,是场景进入并且过渡动画完成时候触发,判断为true情况下,然后通过代码self:onEnterTransitionFinish()调用第⑨行的GameScene:onEnterTransitionFinish()函数。
第④行是判断exit事件,是场景退出时候触发,判断为true情况下,然后通过代码self:onExit()调用第⑩行的GameScene:onExit()函数。
第⑤行是判断exitTransitionStart事件,是场景退出过渡动画开始时候触发,判断为true情况下,然后通过代码self:onExitTransitionStart()调用第?行的GameScene:onExitTransitionStart()函数。
第⑥行是判断cleanup事件,是场景销毁时候触发,判断为true情况下,然后通过代码self:cleanup()调用第?行的GameScene:cleanup()函数。
如果GameScene是第一个场景,当启动GameScene场景时候,它的调用顺序如下图所示。
if event == enter then②
self:onEnter()
elseif event == enterTransitionFinish then③
self:onEnterTransitionFinish()
elseif event == exit then④
self:onExit()
elseif event == exitTransitionStart then⑤
self:onExitTransitionStart()
elseif event == cleanup then⑥
self:cleanup()
end