Cocos 2d game simple collision detection

- (id)init {
//	NSLog(@\"Game::init\");
	
	if(![super init]) return nil;
	
	gameSuspended = YES;

	AtlasSpriteManager *spriteManager = (AtlasSpriteManager*)[self getChildByTag:kSpriteManager];

	[self initPlatforms];
	
	AtlasSprite *bird = [AtlasSprite spriteWithRect:CGRectMake(608,16,44,32) spriteManager:spriteManager];
	[spriteManager addChild:bird z:4 tag:kBird];

	AtlasSprite *bonus;

	for(int i=0; i<kNumBonuses; i++) {
		bonus = [AtlasSprite spriteWithRect:CGRectMake(608+i*32,256,25,25) spriteManager:spriteManager];
		[spriteManager addChild:bonus z:4 tag:kBonusStartTag+i];
		bonus.visible = NO;
	}

//	LabelAtlas *scoreLabel = [LabelAtlas labelAtlasWithString:@\"0\" charMapFile:@\"charmap.png\" itemWidth:24 itemHeight:32 startCharMap:' '];
//	[self addChild:scoreLabel z:5 tag:kScoreLabel];
	
	BitmapFontAtlas *scoreLabel = [BitmapFontAtlas bitmapFontAtlasWithString:@\"0\" fntFile:@\"bitmapFont.fnt\"];
	[self addChild:scoreLabel z:5 tag:kScoreLabel];
	scoreLabel.position = ccp(160,430);

	[self schedule:@selector(step:)];
	
	isTouchEnabled = YES;
	isAccelerometerEnabled = YES;

	[[UIAccelerometer sharedAccelerometer] setUpdateInterval:(1.0 / kFPS)];
	
	[self startGame];
	[self schedule:@selector(gameLogic:) interval:5.0];
	return self;
	
	
}



-(void)addTarget {
	
	Sprite *target = [Sprite spriteWithFile:@\"waa.gif\"];
	target.position = ccp(300,400);
	
	[self addChild:target];
	
	
	
	CGSize winSize = [[Director sharedDirector]winSize];
	int minX = target.contentSize.height/2;
	int maxX = winSize.height -target.contentSize.height/2;
	int rangeX = maxX - minX;
	int actualX = (arc4random() % rangeX) +minX;
	
	int minDuration = 2.0;
	int maxDuration = 4.0;
	int rangeDuration = maxDuration - minDuration;
	int actualDuration = (arc4random() % rangeDuration) + minDuration;
	
	id actionMove = [MoveTo actionWithDuration:actualDuration position:ccp(-target.contentSize.width/2,actualX)];
	id actionMoveDone = [CallFuncN actionWithTarget:self selector:@selector(spriteMoveFinished:)];
	[target runAction:[Sequence actions:actionMove, actionMoveDone,nil]];
	
	
}


-(void)spriteMoveFinished:(id)sender {
	Sprite *sprite = (Sprite *)sender;
	[self removeChild:sprite cleanup:YES];
}
-(void)gameLogic:(ccTime)dt {
	[self addTarget];
	
	
}