Cocos2d - Alternative for CCNode userData - cocos2d-iphone

Question

I am using CCNode userData property to define whether a touched sprite has had a node built upon it (using Ray Wenderlich's - Tower Defence Tutorial).
The problem I am having is that for every new sprite position I touch and build upon, the previous ones are not retained in the sense that I am unable to sell the building built on it using my sell method.
What is the best way to save data to an individual CCSprite that is selected by touch, and defined by a property through a for loop?
I have read that subclassing CCSprite is an option, or creating a struct for userData etc. I have tried to implement these strategies but have been unsuccessful getting them to work.
touch method with sprite property:
-(void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
for(UITouch *touch in touches){
CGPoint location = [touch locationInView:[touch view]];
location = [[CCDirector sharedDirector] convertToGL:location];
for(CCSprite *tb in self.BuildPositions){
//BuildPositions contains CCSprites from a class defining build positions and contained in a mutable array.
if(CGRectContainsPoint([tb textureRect],[tb convertToNodeSpace:location ])){
_selectedBuildPosition = tb;
[self buildMenuTapped];
}
}
}
}
build menu method:
-(void)buildMenuTapped{
[self removeChild:_buildSelectMenu cleanup:YES];
[self removeChild:_sellBuildingMenu cleanup:YES];
if (_selectedBuildPosition.userData == nil) {
CCMenuItem *buildOption = [CCMenuItemImage itemWithNormalImage:#"building.png" selectedImage:#"building.png" target:self selector: #selector(buildOption)];
buildOption.position = ccpAdd(_selectedBuildPosition.position,ccp(0,40));
_buildSelectMenu = [CCMenu menuWithItems:BuildOption, nil];
_buildSelectMenu.position = CGPointZero;
[self addChild:_buildSelectMenu z:100];
}else{
[self sellBuildingMenu];
}
}
build upon method:
-(void)buildOption{
if([self canBuyBuilding] && !_selectedBuildPosition.userData){
_playerEssence -= kBUILD_COST;
_lvl1BuildNodeInstance = [lvl1BuildNode nodeWithTheGame:self location:_selectedBuildPosition.position];
//method as seen in RW tutorial. Generates a lvl1BuildNode class node within the HelloWorldLayer.
_selectedBuildPosition.userData = (__bridge void*)(_lvl1BuildNodeInstance);
}
}
sell menu method:
-(void)sellBuildingMenu{
[self removeChild:_buildSelectMenu cleanup:YES];
[self removeChild:_sellBuildingMenu cleanup:YES];
CCMenuItem *buildingSell = [CCMenuItemImage itemWithNormalImage:#"sell.png" selectedImage:#"sell.png" target:self selector:#selector(sellBuilding)];
buildingSell.position = ccpAdd(_selectedBuildPosition.position,ccp(40,0));
_sellBuildingMenu = [CCMenu menuWithItems:buildingSell, nil];
_sellBuildingMenu.position = CGPointZero;
[self addChild:_sellBuildingMenu z:100];
}
sell method:
-(void)sellBuilding{
if (_selectedBuildPosition.userData == (__bridge void*)(_lvl1BuildNodeInstance)){
[self removeChild:_lvl1GemNodeInstance cleanup:YES];
[_buildings removeObject:_lvl1BuildNodeInstance];
_playerEssence += kBUILD_COST;
_selectedBuildPosition.userData = nil;
}else{
}
}
Thank you for your time.