Delete child SKSpriteNode

Question

Basically I am trying to make it so that when the user hits a fuel tank the old tank disappears and a new one is spawned in a random location. Right now it's detecting the collision but I can't get rid of the child. It will just add a new fuel tank without getting rid of the old one.

What can I do to remove the old child and generate a new one? removefromparent and removeallchildren is not working(nslog shows "move" s I am definitely getting to that statement after a detected collision)

- (void) fuelGenerate {
    //make a fuel tank

    for (int j=1; j<2; j++) {
        SKSpriteNode *fuel = [SKSpriteNode spriteNodeWithImageNamed:@"fuel.png"];

        fuel.position = CGPointMake(arc4random_uniform(self.frame.size.width), arc4random_uniform(self.frame.size.height));
        [fuel setScale:0.6];
        fuel.zPosition = 1;
        fuel.shadowCastBitMask = 1;

        fuel.name = @"fuelNode";
        fuel.physicsBody = [SKPhysicsBody bodyWithRectangleOfSize:fuel.frame.size];

        fuel.physicsBody.dynamic = FALSE;

        fuel.physicsBody.affectedByGravity = false;
        fuel.physicsBody.usesPreciseCollisionDetection = YES;
        fuel.physicsBody.categoryBitMask = fuelCategory;

        fuel.physicsBody.collisionBitMask = fuelCategory | fireCategory;
        fuel.physicsBody.contactTestBitMask = fireCategory;


        if (FuelGen == 1) {

            [self addChild:fuel];

        } else if (FuelGen == 0) {

            NSLog(@"Move");

            [fuel removeFromParent];
            [self addChild:fuel];
            FuelGen == 1
        }

    }
}

Answer 1

Here are some observations:

You your code inside of a loop which only runs once. Why are you doing that?

If you are creating an object, in your case a SKSpriteNode, and want to delete it later on, you will need to keep some kind of reference to it. There are several ways of doing which include creating a property or adding the object to an array.

Your IF statement in its current position does not make any sense. Your code is in the middle of creating a SKSpriteNode but your IF statement only ads the node if FuelGen == 1. IF NOT it tries to remove the node which by itself should throw an error because you have not yet added it.

Lastly, when you are using an IF - ELSE IF statement, you should have an ELSE at the end to catch anything else that did not trigger any of the previous IF statements.

---

To create a SKSpriteNode property add this code between your import(s) and @implementation.

@property (nonatomic, strong) SKSpriteNode *mySprite;

Now you have a property.

To use a NSMutableArray you would do make the array a property and then do something like this:

SKSpriteNode *myNode = [SKSpriteNode spriteWith....
myNode.name = @"SomeUniqueName";
[self addChild:myNode];
[myArray addObject:myNode];

Now you have created a sprite and added to your array and have a reference to it.

Answer 2

You don't seem to have a reference to the "old" fuel tank. All your routine is doing is creating a new fuel sprite and adding it to "self" as a child.

You need to get a reference to the old fuel sprite and remove that. In your code, the [fuel removeFromParent] is referring to the new fuel sprite that you just created in that code above, not the old fuel tank that you're wanting to remove.

The way you do this depends on your actual implementation; if you only have one fuel tank, you can just keep a reference to it, for instance. If you have many, then a more sophisticated system will be required, such as storing them in an array, or setting up your messaging to pass in the fuel node to your code. But either way, you'll never be able to remove the old fuel node unless you have a reference to it in your code.