首先看看在MenuScene.cpp如是如何调用起对话框的
void MenuScene::popupLayer(){
    // 定义一个弹出层，传入一张背景图
    PopupLayer* popDialog = PopupLayer::create(DIALOG_BG);
    // ContentSize 是可选的设置，可以不设置，如果设置把它当作 9 图缩放
    popDialog->setContentSize(CCSizeMake(Quit_Dialog_Size_Width,Quit_Dialog_Size_Height)); 
    popDialog->setTitle(DIALOG_TITLE);
    popDialog->setContentText(DIALOG_CONTENT,20,60,250);
    // 设置回调函数，回调传回一个 CCNode 以获取 tag 判断点击的按钮
    popDialog->setCallbackFunc(this,callfuncN_selector(MenuScene::quitButtonCallback));
    // 添加按钮，设置图片，文字，tag 信息
    popDialog->addButton(BUTTON_BG1,BUTTON_BG3,OK,Btn_Quit_OK_TAG);
    popDialog->addButton(BUTTON_BG2,CANCEL,Btn_Quit_Cancel_TAG);
    this->addChild(popDialog);// 添加到当前层
}

const int Pop_FontSize = 20;//定义字体大小
class PopupLayer :public Layer
{
	static PopupLayer * create(const char* backgroundImage);//根据背景图创建对象
	void setTitle(const char* title,int fontsize=Pop_FontSize);//设置对话框标题
	void setContentText(const char* text,int fontsize=Pop_FontSize,int padding=50,int paddintTop=100);//设置对话框文本内容
	void setCallbackFunc(Object* target,SEL_CallFuncN callfun);//设置按键回调方法
	bool addButton(const char* normalImage,const char* selectedImage,const char* title,int tag=0);//添加对话框按键，如确认取消
	virtual void onEnter();//当进入时调用
	virtual void onExit();//
void buttonCallback(CCObject* pSender);
    int m_contentPadding;// 文字内容两边的空白区距离
int m_contentPaddingTop;  //文字上边空白区距离
 CCObject* m_callbackListener;
SEL_CallFuncN m_callback;
//定义具有retain属性的变量
    CC_SYNTHESIZE_RETAIN(Menu*,m__pMenu,MenuButton);
CC_SYNTHESIZE_RETAIN(Sprite*,m__sfBackGround,SpriteBackGround);
…………………….
};

PopupLayer.cpp部分代码如下：

PopupLayer::PopupLayer():m__pMenu(NULL),m_contentPadding(0),m_contentPaddingTop(0),m_callbackListener(NULL),m_callback(NULL),m__sfBackGround(NULL),m__s9BackGround(NULL),m__ltContentText(NULL),m__ltTitle(NULL)
{ 
}
//释放变量
PopupLayer::~PopupLayer()
{
    CC_SAFE_RELEASE(m__pMenu);
    CC_SAFE_RELEASE(m__sfBackGround);
    CC_SAFE_RELEASE(m__ltContentText);
    CC_SAFE_RELEASE(m__ltTitle);
    CC_SAFE_RELEASE(m__s9BackGround);
}

void PopupLayer::setCallbackFunc(cocos2d::Object *target,SEL_CallFuncN callfun)
{
//menuItem根据调传入的对象，会进行方法的回调
    m_callbackListener = target;
    m_callback = callfun;    
}

bool PopupLayer::init()
{     
        // 初始化需要的 Menu，随后跟进参数向menu中添加Item选项
        Menu* menu = Menu::create();
        menu->setPosition(CCPointZero);
        setMenuButton(menu);
setTouchMode(Touch::DispatchMode::ONE_BY_ONE);
auto listener = EventListenerTouchOneByOne::create();
        listener->setSwallowTouches(true);
  listener->onTouchBegan = [](Touch *t,Event *e){
CCLog("PopupLayer touch");
           return true;
    };
	_eventDispatcher->addEventListenerWithSceneGraPHPriority(listener,this);//屏蔽下层事件响应
	return true;
}

根据参数，标题，tag ，图片效果，添加MenuItem选项
bool PopupLayer::addButton(const char *normalImage,const char *selectedImage,const char *title,int tag)
{
Size winSize = CCDirector::getInstance()->getWinSize();
    Point pCenter = ccp(winSize.width / 2,winSize.height / 2);
    // 创建MenuItem按钮,并设置回调方法
    MenuItemImage* menuImage = MenuItemImage::create(normalImage,selectedImage,this,menu_selector(PopupLayer::buttonCallback));
    menuImage->setTag(tag);
    menuImage->setPosition(pCenter);
    // 给MenuItem添加文字说明并设置在MenuItem中位置
Size imenu = menuImage->getContentSize();
    LabelTTF* ttf = LabelTTF::create(title,"",20);
    ttf->setColor(ccc3(0,0));
    ttf->setPosition(ccp(imenu.width / 2,imenu.height / 2));
    menuImage->addChild(ttf);
    getMenuButton()->addChild(menuImage);
    return true;

现在来看MenuItem的回调方法buttonCallback

void PopupLayer::buttonCallback(cocos2d::CCObject *pSender)
{
    Node* node = dynamic_cast<Node*>(pSender);
    CCLog("touch tag: %d",node->getTag());
    if (m_callback && m_callbackListener){
        (m_callbackListener->*m_callback)(node);//这会调用setCallbackFunc（）方法传入的MenuScene对象的quitButtonCallback（）方法
    }
    this->removeFromParent();//把对话框从父节点移除 
}

对话框弹出前调用onEnter方法进行界面初始化工作

void PopupLayer::onEnter()
{
…………………..
    Size contentSize;
    // 设置对话框背景，代码省略
    // 添加按钮，并设置其位置
    this->addChild(getMenuButton());
    float btnWidth = contentSize.width / (getMenuButton()->getChildrenCount() + 1);
Vector<Node*> vecArray = getMenuButton()->getChildren();
	int j=0;
	for(auto it=vecArray.begin();it!=vecArray.end();it++)
	{
		Node* node = dynamic_cast<Node*>(*it);
		node->setPosition(Point(winSize.width/2 - contentSize.width/2+btnWidth*(j+1),winSize.height/2-contentSize.height/3));
		j++;
	}

    // 显示对话框标题内容省略
    // 添加对话框弹出效果
    Action* popupLayer = Sequence::create(ScaleTo::create(0.0,0.0),ScaleTo::create(0.15,1.05),ScaleTo::create(0.08,0.95),1.0),NULL);
   this->runAction(popupLayer);
}

代码写的稍微多了些，为便于测试，我把代码上传一下，下载地址如下：

未完待续……………………………