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：