cocos2d iphone - What is the correct way of changing image of existing CCSprite?

How do I correctly change sprite to show another image? Or to have another texture? This is the way I do it now. When I need to change sprite image I increase state variable. So i have one picture for 0, another for 1 and another for 2. First i tried just saying mysprite = [CCSpriteWithFile:@"sprite.png"] but that didn't end up too well since I was making new objects every frame and it got messy pretty fast. So I added a check. There is another variable that is stateChanged and it starts at zero. So I compare state to stateChanged before actually making any sprites and if it differs I do the magic. But here comes the problem. Somehow this sprite won't flip. And I believe the problem is in this method.

- (void) updateState
    {
        if (stateChanged != state) {

        if (state == 0)
            {
                currentSprite = [CCSprite spriteWithFile:@"eggclosed.png"];

                [self addChild:currentSprite];
            }

        if (state == 1)

        {
            currentSprite = nil;
            [self removeAllChildrenWithCleanup:YES];
            currentSprite = [CCSprite spriteWithFile:@"eggopen.png"];
            [self addChild:currentSprite];

        }

        if (state == 2)
        {
            currentSprite = nil;
            [self removeAllChildrenWithCleanup:YES];
            currentSprite = [CCSprite spriteWithFile:@"yoshi.png"];
            [self addChild:currentSprite];
        }


            stateChanged = state;
        }
            }

TLDR: How to correctly change image of sprite. I have a Pet object that has a CCSprite property. And I sometimes need to change sprte to look another way. How do?

Answer

CCTexture2D* tex = [[CCTextureCache sharedTextureCache] addImage:@"new_image_name"];
[spriteWant2Change setTexture: tex];