COCOS2D - Removing a child if it collides with another sprite

Question

I am working on a game that has the player controlling a spaceShip. I want to make it such that if the spaceShip sprite collides with spaceJunk the junk disappears.

Here is my code so far.

HelloWorldLayer.h

 #import <GameKit/GameKit.h>


   // HelloWorldLayer
   @interface HelloWorldLayer : CCLayerColor
{
CCSprite *_starShip;
CCSprite *_Paddle1;
CCSprite *_paddle2;

}

// returns a CCScene that contains the HelloWorldLayer as the only child
+(CCScene *) scene;

@end

HelloWorldLayer.M

// Import the interfaces
#import "HelloWorldLayer.h"

// Needed to obtain the Navigation Controller
#import "AppDelegate.h"

#pragma mark - HelloWorldLayer

// HelloWorldLayer implementation

//Import SpaceThings

#import "SpaceThings.h"

@implementation HelloWorldLayer{

}


// Helper class method that creates a Scene with the HelloWorldLayer as the only child.
+(CCScene *) scene
{
    // 'scene' is an autorelease object.
    CCScene *scene = [CCScene node];

    // 'layer' is an autorelease object.
    HelloWorldLayer *layer = [HelloWorldLayer node];

    // add layer as a child to scene
    [scene addChild: layer];

    // return the scene
    return scene;
}

-(void)gameLgoic:(ccTime)dt
{
    [self addSpaceThings];
}


-(void) addSpaceThings
{
   // _junk = [CCSprite spriteWithFile:@"catplaceholder.png"];

    SpaceThings * spaceThings = nil;

    if (arc4random() % 2 == 0){
        spaceThings = [[[Astroids alloc] init] autorelease];
    }else{
        spaceThings = [[[SpaceJunk alloc]init] autorelease];

    }

    //determine where to spawn the space junk along the X-axis
    CGSize winSize = [CCDirector sharedDirector].winSize;
    int minX = spaceThings.contentSize.width/2;
    int maxX = winSize.width - spaceThings.contentSize.width/2;
    int rangeX =maxX - minX;
    int actualX = (arc4random() % rangeX) + minX;


    //spawn the sprite slightly above the screen
    spaceThings.position = ccp(actualX, winSize.height+_starShip.contentSize.height/2);
    [self addChild:spaceThings];

    //set the speed of junk
    int minDuration = spaceThings.minMoveDirection;
    int maxDuarton = spaceThings.maxMoveDirection;
    int rangeDuration = maxDuarton - minDuration;
    float actualDuraton = (arc4random() % rangeDuration)+ minDuration;

    //move junk logic
    CCMoveTo * actionMove = [CCMoveTo actionWithDuration:actualDuraton position:ccp(actualX, -spaceThings.contentSize.height/2)];
    CCCallBlockN *actionMoveDone = [CCCallBlockN actionWithBlock:^(CCNode *node){[node removeFromParentAndCleanup:YES];}];
    [spaceThings runAction:[CCSequence actions:actionMove, actionMoveDone, nil]];

    if (CGRectIntersectsRect(_starShip.boundingBox, spaceThings.boundingBox)){
        [self removeChild:spaceThings cleanup:YES];

    }




}

// on "init" you need to initialize your instance
-(id) init
{
    if (self =[super initWithColor:ccc4(255,255,255,255)]){
        CGSize winSize = [CCDirector sharedDirector].winSize;
        _starShip = [CCSprite spriteWithFile:@"theShip.gif"];
        _starShip.position = ccp(winSize.width/2, 1.25*_starShip.contentSize.height);
        //make the starship appear
        [self addChild:_starShip];

        //make the paddles
        //bottom left one
        _Paddle1 = [CCSprite spriteWithFile:@"spritePaddle.jpeg"];
        int bottomOfScreenX = 0 + _Paddle1.contentSize.width/2;
        int bottomOfScreenY = 0+_Paddle1.contentSize.height/2;
        _Paddle1.position = ccp(bottomOfScreenX,bottomOfScreenY);
        [self addChild:_Paddle1];
        //bottom right one
        _paddle2 = [CCSprite spriteWithFile:@"spritePaddle.jpeg"];
        int bottomRightOfScreenX = winSize.width - _paddle2.contentSize.width/2;
        _paddle2.position = ccp(bottomRightOfScreenX, bottomOfScreenY);
        [self addChild:_paddle2];


        //make thingsInSpace spawn at a set interval

        int setInterval = (arc4random() % 3);
        [self schedule:@selector(gameLgoic:) interval:setInterval];
        //enable touch
        [self setIsTouchEnabled:YES];



    }
    return self;
}

// on "dealloc" you need to release all your retained objects
- (void) dealloc
{
    // in case you have something to dealloc, do it in this method
    // in this particular example nothing needs to be released.
    // cocos2d will automatically release all the children (Label)

    // don't forget to call "super dealloc"
    [super dealloc];

}

-(void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    //make the screens and create events
    CGSize winSize = [CCDirector sharedDirector].winSize;
    NSSet *allTouches = [event allTouches];
    UITouch *touch = [allTouches anyObject];
    CGPoint location = [touch locationInView:[touch view]];
    location = [[CCDirector sharedDirector] convertToGL:location];

    //check to see if the left paddle is being pressed
    if (CGRectContainsPoint([_Paddle1 boundingBox], location)){
         int bottomLeftOfScreenX = 0 + _Paddle1.contentSize.width/1.25;
        //make an action
        //the Y-coordinate of starShip must be the same since the ship must move parallel to it.
       id action = [CCMoveTo actionWithDuration:2 position:ccp(bottomLeftOfScreenX,1.25*_starShip.contentSize.height) ];
        //have starship call this action
        [_starShip runAction:action];
        [action setTag:1];

    }
    //check to see if the right paddle is being pressed
    if (CGRectContainsPoint([_paddle2 boundingBox], location)){
        int bottomRightOfScreenX = winSize.width - _paddle2.contentSize.width/1.25;
        //make an action
        //the Y-coordinate of starShip must be the same since the ship moves parallel to it
        id action2 = [CCMoveTo actionWithDuration:2 position:ccp(bottomRightOfScreenX,1.25*_starShip.contentSize.height) ];
        //starShip is now running this specified action
        [_starShip runAction:action2];
        [action2 setTag:2];
    }


}

-(void)ccTouchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
   //if the player stops touching the pads, all the aciton should stop.

    //left button stop
    [_starShip stopActionByTag:1];
    //right button stop
    [_starShip stopActionByTag:2];

}

#pragma mark GameKit delegate

-(void) achievementViewControllerDidFinish:(GKAchievementViewController *)viewController
{
    AppController *app = (AppController*) [[UIApplication sharedApplication] delegate];
    [[app navController] dismissModalViewControllerAnimated:YES];
}

-(void) leaderboardViewControllerDidFinish:(GKLeaderboardViewController *)viewController
{
    AppController *app = (AppController*) [[UIApplication sharedApplication] delegate];
    [[app navController] dismissModalViewControllerAnimated:YES];
}
@end

spaceThings.h

#import <Foundation/Foundation.h>
#import "cocos2d.h"

@interface SpaceThings : CCSprite
@property (nonatomic, assign) int minMoveDirection;
@property (nonatomic, assign) int maxMoveDirection;

-(id)initWithFile:(NSString *)file minMoveDirection:(int)minMoveDirection maxMoveDirection:(int)maxMoveDirection;

@end

@interface Astroids : SpaceThings
@end

@interface SpaceJunk : SpaceThings
@end

SpaceThings.M

#import "SpaceThings.h"


@implementation SpaceThings

-(id)initWithFile:(NSString *)file minMoveDirection:(int)minMoveDirection maxMoveDirection:(int)maxMoveDirection
{
    if ((self =[super initWithFile:file])){
    self.minMoveDirection = minMoveDirection;
    self.maxMoveDirection = maxMoveDirection;
    }
    return self;
}

@end

@implementation Astroids

-(id)init
{
    if (self = [super initWithFile:@"astroid.jpeg" minMoveDirection:2 maxMoveDirection:5]){

    }
    return self;
}

@end

@implementation SpaceJunk
-(id)init
{
    if (self = [super initWithFile:@"blueDot.jpg" minMoveDirection:4 maxMoveDirection:7]){

    }
    return self;
}


@end   

I'm wondering as to where to put CGRectInteresectRect part of the code. As I've currently tried placing within the SpaceJunk alloc init part and it doesn't remove the child when the ship collides with the junk.

Answer 1

    int setInterval = (arc4random() % 3);
    [self schedule:@selector(gameLgoic:) interval:setInterval];

Make setInterval value to float and give small value for schedular.

Also not do [spaceThings runAction inside loop. if required then do some condition check and run only if required.

Then your CGRectIntersectsRect will fire when intersect each other.

Happy Coding.