cocos2d-x 2.2.1异步加载图片

bool HelloWorld::init(){       bool bRet = false;    do {        CC_BREAK_IF(!CCLayer::init());                        CCTextureCache::sharedTextureCache()->addImageAsync("CloseNormal.png", this, callfuncO_selector(HelloWorld::loadImageFish));                bRet = true;    } while (0);    return bRet;}void HelloWorld::loadImageFish(CCObject* sender){    this->scheduleOnce(schedule_selector(HelloWorld::doLoadImage), 2);    }void HelloWorld::doLoadImage(float delta){        CCSize winSize = CCDirector::sharedDirector()->getWinSize();    CCSprite* bg = CCSprite::create("background.png");    bg->setPosition(ccp(winSize.width / 2,winSize.height / 2));    CCSize bgSize = bg->getContentSize();    float f = MAX(winSize.width / bgSize.width, winSize.height / bgSize.height);    bg->setScale(f);    this->addChild(bg);   }