//Create our scrolling background
- (void)setupBackgroundImage
{
    //create both sprite to handle background
    background1 = [CCSprite spriteWithFile:@"cloud_bg1.png"];
    background2 = [CCSprite spriteWithFile:@"cloud_bg2.png"];
    
    background1.position = ccp(0, size.height/2);
    background2.position = ccp(size.width, size.height/2);
    
    //add them to main layer
    [self addChild:background1 z:0];
    [self addChild:background2 z:0];
    
    //add schedule to move backgrounds
    [self schedule:@selector(scroll:)];
}

- (void)scroll:(ccTime)dt {
    
    background1.position = ccp( background1.position.x - 2, background1.position.y );
    background2.position = ccp( background2.position.x - 2, background2.position.y );
    
    //reset position when they are off from view.
    if (background1.position.x == - (size.width/2)) {
        background1.position = ccp(size.width+(size.width/2), size.height/2);
    }
    else if (background2.position.x == - (size.width/2)) {
        background2.position = ccp(size.width+(size.width/2), size.height/2);
    }
    
}

Cocos2d Scrolling Background

Objective C