cocos2dx CCControlSlider 滑动条

//滑动条
    CCControlSlider * slider = CCControlSlider ::create("sliderBg.png", "sliderProgress.png", "sliderThumb.png");
    slider->setPosition(ccp(200, 170));
//    设置滑动条最大值
    slider->setMaximumValue(100);
    //    设置滑动条最小值
    slider->setMinimumValue(0);
    addChild(slider,0,921);
//    设置监听 ， 但滑动条的值发生变化后 ， 会相应 valueChanged 函数
//CCControlEventValueChanged值改变
    slider->addTargetWithActionForControlEvents(this, cccontrol_selector(HelloWorld::valueChanged), CCControlEventValueChanged);
//    用于展示当前滑动条的滑动值
    CCLabelTTF * label = CCLabelTTF ::create();
    label->setColor(ccc3(255, 0, 0));
    label->setPosition(ccp(200, 200));
    
    label->setString(CCString::createWithFormat("滑动条当前值＝ %0.02f",slider->getValue())->getCString());
    addChild(label,0,922);

void HelloWorld::valueChanged()
{
//    利用tag 来确定 
    CCControlSlider *  slider = (CCControlSlider * )this->getChildByTag(921);
    CCLabelTTF * label =(CCLabelTTF * )this->getChildByTag(922);
    label->setString(CCString::createWithFormat("滑动条的当前值 ＝ %.02f" ,slider->getValue())->getCString());

}