顾名思义,removeFromParent就是把自己从父亲那里移除,removeAllChildren就是移除自己所有的孩子,这些方法的具体实现都在基类Node里面,通过查看代码也很容易看到怎么实现的。

现在主要看下他们两个的调用顺序

示例代码如下:

比如自定义一个类Layer,

#ifndef _MAINMENU_H1_
#define _MAINMENU_H1_ #include "cocos2d.h"
using namespace cocos2d;
using namespace std;
class Layer1 : public Layer
{
public:
Layer1(); virtual ~Layer1(); bool init(); virtual bool onTouchBegan(Touch *pTouch, Event *pEvent);
virtual void onTouchMoved(Touch *pTouch, Event *pEvent);
virtual void onTouchEnded(Touch *pTouch, Event *pEvent);
virtual void onTouchCancelled(Touch *pTouch, Event *pEvent); string haha; CREATE_FUNC(Layer1); }; #endif
#include "Layer1.h"

Layer1::Layer1()
{ }
Layer1::~Layer1()
{ printf("析构函数"); } bool Layer1::init()
{
// this->setTouchEnabled(true); auto listen = EventListenerTouchOneByOne::create();
listen->onTouchBegan = CC_CALLBACK_2(Layer1::onTouchBegan, this);
listen->onTouchMoved = CC_CALLBACK_2(Layer1::onTouchMoved, this);
listen->onTouchEnded = CC_CALLBACK_2(Layer1::onTouchEnded, this);
listen->onTouchCancelled = CC_CALLBACK_2(Layer1::onTouchCancelled, this);
// listen->setSwallowTouches(true);
Director::getInstance()->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listen, this); return true;
} bool Layer1::onTouchBegan(Touch *touch, Event * pEvent)
{
printf("Layer1 began\n"); this->removeFromParent();
this->removeAllChildren(); // for(int i=0;i<100000;i++){
// printf("char=%s",haha.c_str());
// } return true;
} void Layer1::onTouchEnded(Touch *touch, Event * pEvent)
{
printf("Layer1 end\n");
} void Layer1::onTouchCancelled(Touch *touch, Event *pEvent)
{
printf("Layer1 cancel\n");
} void Layer1::onTouchMoved(Touch *touch, Event *pEvent)
{
printf("Layer1 Move\n");
}
AppDelegate
auto scene = Scene::create();
auto layer1=Layer1::create();
scene->addChild(layer1);
director->runWithScene(scene);

当点击界面的时候,会报错,看标红的地方,很容易理解什么原因 removeFromParent之后,Layer1实例已经释放了,在调用就会报错(但是在cocos2d-iphone中,他们的顺序是无关紧要的,都可以正确运行,通过调试得知,当调用RemoveFromPanrent的时候,dealloac没有马上调用,而c++中的析构函数会立即调用,我猜想原因可能就在这里吧),然后把顺序反过来,果然正确执行.

下面再看下一个问题,移除Layer1实例的时候,能否只调用removeFromParent,而不调用removeAllChildren().这个可以通过析构函数来判断,新建一个Layer2的类

#ifndef _MAINMENU_H222_
#define _MAINMENU_H222_ #include "cocos2d.h"
using namespace cocos2d; class Layer2 : public Layer
{
public:
Layer2(); virtual ~Layer2(); bool init(); virtual bool onTouchBegan(Touch *pTouch, Event *pEvent);
virtual void onTouchMoved(Touch *pTouch, Event *pEvent);
virtual void onTouchEnded(Touch *pTouch, Event *pEvent);
virtual void onTouchCancelled(Touch *pTouch, Event *pEvent); CREATE_FUNC(Layer2); }; #endif
#include "Layer2.h"

Layer2::Layer2()
{
} Layer2::~Layer2(){
printf("Layer2析构函数");
} bool Layer2::init()
{
//this->setTouchEnabled(true); auto listen = EventListenerTouchOneByOne::create();
listen->onTouchBegan = CC_CALLBACK_2(Layer2::onTouchBegan, this);
listen->onTouchMoved = CC_CALLBACK_2(Layer2::onTouchMoved, this);
listen->onTouchEnded = CC_CALLBACK_2(Layer2::onTouchEnded, this);
listen->onTouchCancelled = CC_CALLBACK_2(Layer2::onTouchCancelled, this);
// listen->setSwallowTouches(true);
Director::getInstance()->getEventDispatcher()->addEventListenerWithSceneGraphPriority(listen, this); return true;
} bool Layer2::onTouchBegan(Touch *touch, Event * pEvent)
{
printf("Layer2 began\n"); return true;
} void Layer2::onTouchEnded(Touch *touch, Event * pEvent)
{
printf("Layer2 end\n");
// pEvent->stopPropagation();
} void Layer2::onTouchCancelled(Touch *touch, Event *pEvent)
{
printf("Layer2 cancel\n");
} void Layer2::onTouchMoved(Touch *touch, Event *pEvent)
{
printf("Layer2 Move\n");
pEvent->stopPropagation();
}

Layer1修改,去掉

this->removeAllChildren();这一行代码

Appdelegate

   auto scene = Scene::create();
// scene->addChild(MainMenu::create()); auto layer1=Layer1::create(); //int fff=layer1->getReferenceCount(); auto layer2=Layer2::create();
layer1->addChild(layer2);
scene->addChild(layer1);
// layer2->retain(); // run
director->runWithScene(scene);

通过运行发现,Layer2会执行析构函数,那么Layer2是在什么位置被删除的呢,通过看removeFromParent的源码发现,并没有发现删除Layer2的代码,

而在removeAllChildren()中很容易发现是

_children.clear();但是removeFromParent中并没有这个代码,最后通过分析找到了地方,原来Layer的基类Node有一个_children的Vector数组,当

Node释放的时候,他的属性_children也会释放,然后这个属性会调用析构函数,在析构函数里面调用了clear()方法,如下代码

/** Destructor */

~Vector<T>()

{

CCLOGINFO("In the destructor of Vector.");

clear();

},

,从而使Layer1的孩子Layer2也释放。

所以分析得知,要移除某个cocos2d类的实例,在保证没有内存泄露的情况下(内存泄露的话,两个方法都调也不行),调用 removeFromParent就可删除自身,无需调用removeAllChildren(),如果两个类都想调用,那么先调用removeAllChildren,在调用removeFromParent。

05-08 08:16