Keeping track of sprites - iphone

Question

I'm creating a Cocos2D app that will have between 4 - 12 sprites that the user can interact with/move (Sprites 1 - 4 in the pic). There will be an equal number of target sprites that the user will be able to drag the other sprites to (Targets 1 - 4 in the pic). I was thinking about adding tags to all of the sprites to differentiate between them. What I'm having difficulty with is determining the proper way to keep track of the moveable sprites in relation to what target sprites each of them are on top of.
How should I keep track of these relationships?
Sprite 1 - Target 3
Sprite 2 - Target 1
Sprite 3 - Target 2
Sprite 4 - Target 4

Answer 1

Create two different isntance mutable arrays to hold your objects and an array to hold your correct answers i.e.
//In your .h
NSMutableArray *_targets;
NSMutableArray *_moveableSprites;
NSArray *_answers;
//In your .m
_targets = [[NSMutableArray alloc] init];
_moveableSprites = [[NSMutableArray alloc] init];
_answers = [[NSArray alloc] initWithObjects:#"101", #"103", #"102", #"104", nil];
When you create your sprites assign a tag value to them i.e.
CCSprite *target1 = [CCSprite spriteWithFile:#"file.png"];
//Make sure target tags start from 0 and increment up
target1.tag = 0;
Then before you add each sprite to your layer add them into your respective arrays i.e.
[_targets addObject:target1];
You can then write a method to check sprite position (something similar to this):
- (void)checkSprites {
for(CCSprite *sprite in _moveableSprites) {
for(CCSprite *target in _targets) {
if(CGRectIntersectsRect(sprite.boundingBox, target.boundingBox)) {
if(sprite.tag == [_answers objectAtIndex:target.tag]) {
// Correct sprite in target.....do stuff
} else {
// Not correct sprite.....do stuff
}
}
}
}
}