背景图片循环滚动 使用action 实现的：

主要有两个背景图片交替循环滚动：我选的两个背景图片的宽度都是1024的 ，所以定义了#define BGIMG_WIDTH 1024

代码如下：

在HelloWorld.h的头文件中声明两个背景图片精灵

#import "cocos2d.h"

// HelloWorldLayer

@interface HelloWorldLayer : CCLayer

{

    CCSprite *bagSprite1;

    CCSprite *bagSprite2;

}

在.m文件中实现的部分代码：

#import "HelloWorldLayer.h"

#import "AppDelegate.h"

#pragma mark - HelloWorldLayer

#define BGIMG_WIDTH 1024

// HelloWorldLayer implementation

@implementation HelloWorldLayer

-(id) init

{

	if( (self=[super init]) ) {

        CGSize winSize=[CCDirector sharedDirector].winSize;

        bagSprite1=[CCSprite spriteWithFile:@"bag1.jpg"];

        bagSprite2=[CCSprite spriteWithFile:@"bag2.jpg"];

        bagSprite1.anchorPoint=ccp(0,0);

        bagSprite2.anchorPoint=ccp(0,0);

        [bagSprite1 setScaleY:winSize.height/bagSprite1.textureRect.size.height];   //修改背景图片的高度

        [bagSprite2 setScaleY:winSize.height/bagSprite2.textureRect.size.height];

        bagSprite1.position=ccp(0,0);

        bagSprite2.position=ccp(-BGIMG_WIDTH,0);    //第二张图片的起始位置在第一张的左边

        //添加精灵

        [self addChild:bagSprite1 z:1];

        [self addChild:bagSprite2 z:1];

        CCMoveBy *bagSprite1MoveBy=[CCMoveBy actionWithDuration:6.0f position:ccp(BGIMG_WIDTH,0)];

        CCMoveBy *bagSprite2MoveBy=[CCMoveBy actionWithDuration:6.0f position:ccp(BGIMG_WIDTH,0)];

        CCCallBlock *bagSprite1Finish=[CCCallBlock actionWithBlock:^(void){[self actionFinishedWithSprite:bagSprite1];}];

        CCCallBlock *bagSprite2Finish=[CCCallBlock actionWithBlock:^(void){[self actionFinishedWithSprite:bagSprite2];}];

        [bagSprite1 runAction:[CCSequence actions:bagSprite1MoveBy,bagSprite1Finish,nil]];

        [bagSprite2 runAction:[CCSequence actions:bagSprite2MoveBy,bagSprite2Finish,nil]];

	}

	return self;

}

-(void)actionFinishedWithSprite:(CCSprite*)theSprite{

    if(theSprite.position.x==0){

        CCMoveBy *bagSpriteMoveBy=[CCMoveBy actionWithDuration:6.0f position:ccp(BGIMG_WIDTH,0)];

        CCCallBlock *bagSpriteFinish=[CCCallBlock actionWithBlock:^(void){[self actionFinishedWithSprite:theSprite];}];

        [theSprite runAction:[CCSequence actions:bagSpriteMoveBy,bagSpriteFinish,nil]];

    }else if(theSprite.position.x==BGIMG_WIDTH){

        [theSprite setPosition:ccp(-BGIMG_WIDTH,0)];

        CCMoveBy *bagSpriteMoveBy=[CCMoveBy actionWithDuration:6.0f position:ccp(BGIMG_WIDTH,0)];

        CCCallBlock *bagSpriteFinish=[CCCallBlock actionWithBlock:^(void){[self actionFinishedWithSprite:theSprite];}];

        [theSprite runAction:[CCSequence actions:bagSpriteMoveBy,bagSpriteFinish,nil]];

    }

}

@end

运行结果：