Cocos2d: Solid color rectangular sprite with border

Question

Is there a way one could add a border around a plain color sprite without having to create another sprite?

Here the code to create the plain colored rectangular sprite. Thanks goes to Mat Cegiela for sharing it on SO (https://stackoverflow.com/a/14609459/1097106).:

-(CCSprite*)blankSpriteWithSize:(CGSize)size
{
    CCSprite *sprite = [CCSprite node];
    GLubyte *buffer = malloc(sizeof(GLubyte)*4);
    for (int i=0;i<4;i++) {buffer[i]=255;}
    CCTexture2D *tex = [[CCTexture2D alloc] initWithData:buffer pixelFormat:kCCTexture2DPixelFormat_RGB5A1 pixelsWide:1 pixelsHigh:1 contentSize:size];
    [sprite setTexture:tex];
    [sprite setTextureRect:CGRectMake(0, 0, size.width, size.height)];
    free(buffer);
    return sprite;
}

This works great as it doesn't use any image files.

To add a border one could create two plain colored sprites using the above method, one slightly smaller and add the smaller one as a child to the parent sprite, but is there a way one could do it more elegantly?

I tried (https://stackoverflow.com/a/10903183/1097106) -- thanks Morion for sharing it:

CGSize selfSize = [self contentSize];
float selfHeight = selfSize.height;
float selfWidth = selfSize.width;
CGPoint vertices[4] = {ccp(0.f, 0.f), ccp(0.f, selfHeight), ccp(selfWidth, selfHeight), ccp(selfWidth, 0.f)};
ccDrawPoly(vertices, 4, YES);

in the sprite's -(void)draw without any positive result. It doesn't show the sprite at all when adding this code to -(void)draw.

Edit: Turns out the problem was a missing [super draw]; inside -(void)draw. Adding it will make it work.

Here the implementation of -(void)draw that will allow for borders around a plain color rectangular sprite (it also defines a custom color):

-(void)draw
{
    [super draw];

    CGSize selfSize = [self contentSize];
    float selfHeight = selfSize.height;
    float selfWidth = selfSize.width;
    CGPoint vertices[4] = {ccp(0.f, 0.f), ccp(0.f, selfHeight), ccp(selfWidth, selfHeight), ccp(selfWidth, 0.f)};
    ccDrawColor4B(120, 120, 120, 255);
    ccDrawPoly(vertices, 4, YES);
}