Collision detection with sprites from an array in Cocos2D - ios

Question

i'm pretty new to Objective-C and Cocos2D so go easy, I know this is basic stuff.
I'm using an array to randomly place 4 gold coin sprites on the screen, and i'm using another sprite (a dragon) to fly around and collect the coins. Obviously, I want the coin to disappear and another to randomly appear (like collecting apples in Snake). My problem is that I don't know how to reference the individual sprites. I've added some handling to the update method but a) I don't think its appropriate and b) it doesn't do anything. Please help. I think I need to utilise:
[self removeChild:sprite cleanup:YES];
But I'm not sure how. This is how i'm populating the screen with rings::
#implementation MainScene {
CCSprite *_hero;
CCPhysicsNode *_physicsNode;
CCSprite *_goldRing;
NSMutableArray *_goldRings;
}
-(void)didLoadFromCCB {
self.userInteractionEnabled = TRUE;
_goldRing.physicsBody.collisionType = #"Level";
_goldRing.physicsBody.sensor = TRUE;
_physicsNode.collisionDelegate = self;
_hero.physicsBody.collisionType = #"hero";
CGFloat random = ((double)arc4random() / ARC4RANDOM_MAX);
_meteorites = [NSMutableArray array];
[self spawnNewGoldRing];
[self spawnNewGoldRing];
[self spawnNewGoldRing];
[self spawnNewGoldRing];
}
-(void)spawnNewGoldRing {
CGFloat randomX = ((double)arc4random() / ARC4RANDOM_MAX);
CGFloat randomY = ((double)arc4random() / ARC4RANDOM_MAX);
CGFloat rangeX = 200;
CGFloat rangeY = 300;
CCNode *goldRing = [CCBReader load:#"goldRing"];
goldRing.position = ccp(randomX * rangeX, (randomY * rangeY)+100);
[_physicsNode addChild:goldRing];
[_goldRings addObject:goldRing];
}
- (void)update:(CCTime)delta {
_hero.position = ccp(_hero.position.x, _hero.position.y);
if(_hero.position.x <= _hero.contentSize.width/2 * -1.5) {
_hero.position = ccp(_ground.contentSize.width + _hero.contentSize.width/2, _hero.position.y);
NSMutableArray *collectedGoldRings = nil;
for (CCNode *goldRing in _goldRings) {
CGPoint goldRingWorldPosition = [_physicsNode convertToWorldSpace:goldRing.position];
CGPoint goldRingScreenPosition = [self convertToNodeSpace:goldRingWorldPosition];
if (goldRingScreenPosition.x < -goldRing.contentSize.width) {
if (!collectedGoldRings) {
collectedGoldRings = [NSMutableArray array];
}
[collectedGoldRings addObject:goldRing];
}
}
for (CCNode *goldRingToRemove in collectedGoldRings) {
[goldRingToRemove removeFromParent];
[_goldRings removeObject:goldRingToRemove];
// for each removed goldRing, add a new one
[self spawnNewGoldRing];
}
}
}
Would it be too much to ask how to keep count of these too to display a score?
Thanks so much for any help.
EDIT*
NSLog on the array of gold rings
"<goldRing = 0x9b756b0 | Rect = (0.00,0.00,24.00,23.50) | tag = | atlasIndex = -1>"
)
2014-05-08 10:24:32.201 dragonCollector2[10165:60b] Gold Ring Loaded
2014-05-08 10:24:32.201 dragonCollector2[10165:60b] Array:(
"<goldRing = 0x9b77e50 | Rect = (0.00,0.00,24.00,23.50) | tag = | atlasIndex = -1>"

Answer 1

As I see, you are using spritebuilder, so you are using the new version of Cocos2D.
In this version you can track a collision between two types of nodes. In your case, the coins and the hero.
This is as simple as:
1) Set your coin.physicsBody.collisionType = #"coin";
2) Set your hero.physicsBody.collisionType = #"hero";
3) Implement this method:
-(void)ccPhysicsCollisionPostSolve:(CCPhysicsCollisionPair *)pair hero:(CCNode *)nodeA coin:(CCNode *)nodeB{
//this method will be automatically called when the hero hits a coin.
//now call your method to remove the coin and call the method to add another coin.
}
To keep a count of the score, just make an int variable, int score;. In your didLoadFromCCB method, initialize it to 0, score=0; and inside this collision method, just do score++; and maybe do a NSLog(#"Your score:%i",score);
Hope this helps.

Answer 2

for things like that, you do not need to use physics. When your hero will touch a coin, just update the user score (it could be an integer) and the coin position.
in your update method do something like
for(CCSprite *gold in _goldRings){
if(CGRectIntersectsRect(_hero.boundingBox,gold.boundingBox)){
//touched a coin
//do whatever u want
//do not remove the coin from the array, just change it's position!
_userPoints += 1;
gold.position=ccp(arc4random()%200 , arc4random()%300);
break;
}
}