UserDefault可以实现数据的存储，但是它的使用不能泛滥，具体讲一般情况下不会使用它保存大量的数据，它没有SQL语句那样的灵活。UserDefault除了保存游戏设置外，还有可以长期保持游戏精灵等对象的状态。


我们通过一个实例介绍一下在游戏项目中如何使用UserDefault。如图所示，在Setting场景中可以设置是否播放背景音乐和音效，现在我们将它完善将选择的状态保存到UserDefault中。

#ifndef __HELLOWORLD_SCENE_H__
#define __HELLOWORLD_SCENE_H__


#include "cocos2d.h"
#include "SettingScene.h"
#include "SystemHeader.h"


class HelloWorld : public cocos2d::Layer
{
public:
	… …
	CREATE_FUNC(HelloWorld);
};


#endif // __HELLOWORLD_SCENE_H__

#include "HelloWorldScene.h"


USING_NS_CC;
using namespace CocosDenshion;


bool HelloWorld::init()
{
	... ...
	return true;
}


void HelloWorld::menuItemSettingCallback(Ref* pSender)
{	
	auto sc = Setting::createScene();
	auto reScene = TransitionJumpZoom::create(1.0f, sc);
	Director::getInstance()->pushScene(reScene);


	if (UserDefault::getInstance()->getBoolForKey(SOUND_KEY)) {						①
		SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");
	}
}


void HelloWorld::menuItemHelpCallback(Ref* pSender)
{
	MenuItem* item = (MenuItem*)pSender;
	log("Touch Help %p", item);
	if (UserDefault::getInstance()->getBoolForKey(SOUND_KEY)) {						②
		SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");
	}
}


void HelloWorld::menuItemStartCallback(Ref* pSender)
{
	MenuItem* item = (MenuItem*)pSender;
	log("Touch Start %p", item);
	if (UserDefault::getInstance()->getBoolForKey(SOUND_KEY)) {						③
		SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");
	}
}


void HelloWorld::onEnter()
{
	Layer::onEnter();
	log("HelloWorld onEnter");		
}


void HelloWorld::onEnterTransitionDidFinish()
{
	Layer::onEnterTransitionDidFinish();
	log("HelloWorld onEnterTransitionDidFinish");


	//播放
	if (UserDefault::getInstance()->getBoolForKey(MUSIC_KEY)) {						④
		SimpleAudioEngine::getInstance()->playBackgroundMusic("sound/Jazz.mp3", true);
	}
}


void HelloWorld::onExit()
{
	Layer::onExit();
	log("HelloWorld onExit");
}


void HelloWorld::onExitTransitionDidStart()
{
	Layer::onExitTransitionDidStart();
	log("HelloWorld onExitTransitionDidStart");
}


void HelloWorld::cleanup()
{
	Layer::cleanup();
	log("HelloWorld cleanup");	
	//停止
	SimpleAudioEngine::getInstance()->stopBackgroundMusic("sound/Jazz.mp3");
}

#include "SettingScene.h"


USING_NS_CC;
using namespace CocosDenshion;


bool Setting::init()
{
	... ...
	UserDefault *defaults  = UserDefault::getInstance();


	if (defaults->getBoolForKey(MUSIC_KEY)) {									①
		musicToggleMenuItem->setSelectedIndex(0);								②
	} else {
		musicToggleMenuItem->setSelectedIndex(1);								③
	}


	if (defaults->getBoolForKey(SOUND_KEY)) {									④
		soundToggleMenuItem->setSelectedIndex(0);								⑤
	} else {
		soundToggleMenuItem->setSelectedIndex(1);								⑥
	}


	return true;
}

void Setting::menuSoundToggleCallback(Ref* pSender)
{
	auto soundToggleMenuItem = (MenuItemToggle*)pSender;
	log("soundToggleMenuItem %d", soundToggleMenuItem->getSelectedIndex());


	UserDefault *defaults  = UserDefault::getInstance();
	if (defaults->getBoolForKey(SOUND_KEY)) {									①
		defaults->setBoolForKey(SOUND_KEY, false);								②
	} else {
		defaults->setBoolForKey(SOUND_KEY, true);								③
		SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");					④
	}


}

void Setting::menuMusicToggleCallback(Ref* pSender)
{
	auto musicToggleMenuItem = (MenuItemToggle*)pSender;
	log("musicToggleMenuItem %d", musicToggleMenuItem->getSelectedIndex());


	UserDefault *defaults  = UserDefault::getInstance();
	if (defaults->getBoolForKey(MUSIC_KEY)) {									①
		defaults->setBoolForKey(MUSIC_KEY, false);
		SimpleAudioEngine::getInstance()->stopBackgroundMusic();
	} else {
		defaults->setBoolForKey(MUSIC_KEY, true);
		SimpleAudioEngine::getInstance()->playBackgroundMusic("sound/Synth.mp3");
	}																			②
}

void Setting::onEnter()
{
	Layer::onEnter();
	log("Setting onEnter");
}


void Setting::menuOkCallback(Ref* pSender)									①
{
	Director::getInstance()->popScene();


	if (UserDefault::getInstance()->getBoolForKey(SOUND_KEY)) {						②
		SimpleAudioEngine::getInstance()->playEffect("sound/Blip.wav");
	}
}


void Setting::onEnterTransitionDidFinish()										③
{
	Layer::onEnterTransitionDidFinish();
	log("Setting onEnterTransitionDidFinish");	


	if (UserDefault::getInstance()->getBoolForKey(MUSIC_KEY)) {						④
		//播放
		SimpleAudioEngine::getInstance()->playBackgroundMusic("sound/Synth.mp3", true);
	}


}


void Setting::onExit()
{
	Layer::onExit();
	log("Setting onExit");	
}


void Setting::onExitTransitionDidStart()
{
	Layer::onExitTransitionDidStart();
	log("Setting onExitTransitionDidStart");
}


void Setting::cleanup()
{
	Layer::cleanup();
	log("Setting cleanup");	
	//停止
	SimpleAudioEngine::getInstance()->stopBackgroundMusic("sound/Synth.mp3");
}

我们可以运行一下先将状态保存，然后重新运行游戏，看看是否能够保持状态。我们还可以到<Cocos2d-x工程目录>\proj.win32\Debug.win32目录下看看是否成功生成了UserDefault.xml文件。

Cocos2d-x使用UserDefault数据持久化实例：保存背景音乐和音效设置