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Alright, so I'm fairly new to sprite kit and I'm working in Swift. I have 2 sprite nodes, savior and chicken1. savior has a physics body and this is how I set it up: 

var saviorTexture = SKTexture(imageNamed: "1.png")
saviorTexture.filteringMode = SKTextureFilteringMode.Nearest

savior = SKSpriteNode(texture: saviorTexture)
savior.setScale(0.2)
savior.position = CGPoint(x: self.frame.size.width * 0.5, y: self.frame.size.height * 0.2)
savior.physicsBody?.dynamic = true
savior.physicsBody?.allowsRotation = false
savior.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(savior.size.width, savior.size.height))

        self.addChild(savior)

chicken1 right now does not have a physics body:

var chickenTexture = SKTexture(imageNamed: "block1")

        chicken1 = SKSpriteNode(texture: chickenTexture)
        chicken1.setScale(0.75)
        chicken1.position = CGPoint(x: self.size.width * 0.38, y: self.size.height * 1.2)
        self.addChild(chicken1)

I need to know how I can have collision detection (i.e. if savior and chicken1 touch, execute this) between these objects, preferably without making chicken1 a physics body.

When I make chicken1 a physics body, suddenly it becomes erratic and moves other objects around.

If there is not a way to do collision detection without physics, how can I make chicken1 a physics body that is NOT affected by anything and just goes right through the other physics bodies?

EDIT**************

So I followed beginner swift sprite kit - node collision detection help (SKPhysicsContact) and have:

  1. changed my class to be a SKPhysicsContactDelegate:

    class GameScene: SKScene, SKPhysicsContactDelegate {

  2. Written the following:

        self.physicsWorld.contactDelegate = self

    savior.physicsBody?.categoryBitMask = saviorCategory
    savior.physicsBody?.contactTestBitMask = animalCategory
    savior.physicsBody?.collisionBitMask = 0

    chicken1.physicsBody?.categoryBitMask = animalCategory
    chicken1.physicsBody?.contactTestBitMask = saviorCategory
    chicken1.physicsBody?.collisionBitMask = 0

    func didBeginContact(contact: SKPhysicsContact) {

    var saviorPhysics: SKPhysicsBody
    var chicken1Physics: SKPhysicsBody

    if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask
    {
        saviorPhysics = contact.bodyA
        chicken1Physics = contact.bodyB
    }
    else {
        saviorPhysics = contact.bodyB
        chicken1Physics = contact.bodyA
    }

    if saviorPhysics.categoryBitMask == 0 && chicken1Physics.categoryBitMask == 1 {
        self.chicken1.removeFromParent()
    }

}

I ran it and there were no errors, but it doesn't work.

Community
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blue
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1 Answers1

4

You can do this using categoryBitMask and handling the collision yourself by responding to the SKSceneContactDelegate.

This way you can set different categories for different nodes and handle the collision between the different categories as you please.

Tutorial:

http://seodoa.com/2014/04/01/skphysicsbody-react-to-contact-but-not-to-collide/

chrissukhram
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    I looked at that tutorial but its for objective C so I've been following this link, which modifies it for Swift: http://stackoverflow.com/questions/26270504/beginner-swift-sprite-kit-node-collision-detection-help-skphysicscontact – blue Apr 07 '15 at 03:28
  • it doesn't work. savior falls through another physics body that I needed it to collide with and chicken1 does not delete when in contact with savior. – blue Apr 07 '15 at 03:39