spritekit didBeginContact three object not worked - ios

Question

I am tring to [didBeginContact] by three nodes. I wrote under code.
But not work correctly. when white rectangle fole without hitting black or white rectangle,
println("black"), and println("blue") work...
whien white rectangle hit black rectangle, println("blue") work...
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
let blackCategory: UInt32 = 0x1 << 0
let whiteCategory: UInt32 = 0x1 << 1
let blueCategory: UInt32 = 0x1 << 2
override func didMoveToView(view: SKView) {
self.physicsWorld.contactDelegate = self
self.size = view.bounds.size
self.physicsBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
self.physicsWorld.gravity = CGVectorMake(0.0, -3.0)
let blackSquare = SKSpriteNode(color: UIColor.blackColor(), size: CGSizeMake(50, 50))
blackSquare.position = CGPoint(
x: CGRectGetMidX(self.frame),
y: CGRectGetMidY(self.frame)
)
blackSquare.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(50, 50))
blackSquare.physicsBody?.affectedByGravity = false
blackSquare.physicsBody?.dynamic = false
blackSquare.physicsBody?.categoryBitMask = blackCategory
blackSquare.physicsBody?.contactTestBitMask = whiteCategory
let blueSquare = SKSpriteNode(color: UIColor.blueColor(), size: CGSizeMake(50, 50))
blueSquare.position = CGPoint(
x: CGRectGetMidX(self.frame) - 100,
y: CGRectGetMidY(self.frame) - 100
)
blueSquare.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(50, 50))
blueSquare.physicsBody?.affectedByGravity = false
blueSquare.physicsBody?.dynamic = false
blackSquare.physicsBody?.categoryBitMask = blueCategory
blackSquare.physicsBody?.contactTestBitMask = whiteCategory
self.addChild(blackSquare)
self.addChild(blueSquare)
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
for touch in touches {
let location = touch.locationInNode(self)
let whiteRectangle = SKSpriteNode(color: UIColor.whiteColor(), size: CGSizeMake(50, 50))
whiteRectangle.position = location
whiteRectangle.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake(50, 50))
whiteRectangle.physicsBody?.categoryBitMask = whiteCategory
whiteRectangle.physicsBody?.contactTestBitMask = blackCategory
whiteRectangle.physicsBody?.contactTestBitMask = blueCategory
self.addChild(whiteRectangle)
}
}
override func update(currentTime: CFTimeInterval) {
}
func didBeginContact(contact: SKPhysicsContact!) {
var firstBody, secondBody, thirdBody: SKPhysicsBody
if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
firstBody = contact.bodyA
secondBody = contact.bodyB
thirdBody = contact.bodyB
} else {
firstBody = contact.bodyB
secondBody = contact.bodyA
thirdBody = contact.bodyA
}
if firstBody.categoryBitMask & whiteCategory != 0 &&
secondBody.categoryBitMask & blackCategory != 0 {
//secondBody.node?.removeFromParent()
println("black")
}
if firstBody.categoryBitMask & whiteCategory != 0 &&
thirdBody.categoryBitMask & blueCategory != 0 {
//secondBody.node?.removeFromParent()
println("blue")
}
}
}

Answer 1

1) Based on your contact handler, you should set the categories to be
let whiteCategory: UInt32 = 0x1 << 0
let blackCategory: UInt32 = 0x1 << 1
let blueCategory: UInt32 = 0x1 << 2
2) You are incorrectly setting the blackSquare's physicsBody's bit masks twice
blackSquare.physicsBody?.categoryBitMask = blueCategory
blackSquare.physicsBody?.contactTestBitMask = whiteCategory
The above should be
blueSquare.physicsBody?.categoryBitMask = blueCategory
blueSquare.physicsBody?.contactTestBitMask = whiteCategory
3) The third contact body is not needed here.
func didBeginContact(contact: SKPhysicsContact!) {
var firstBody, secondBody: SKPhysicsBody
if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
firstBody = contact.bodyA
secondBody = contact.bodyB
} else {
firstBody = contact.bodyB
secondBody = contact.bodyA
}
if ((firstBody.categoryBitMask & whiteCategory) != 0 &&
(secondBody.categoryBitMask & blackCategory != 0)) {
//secondBody.node?.removeFromParent()
println("black")
}
if ((firstBody.categoryBitMask & whiteCategory != 0) &&
(secondBody.categoryBitMask & blueCategory != 0)) {
//secondBody.node?.removeFromParent()
println("blue")
}
}
4) The following is not needed (in touchesBegan). Setting the contact bit masks for the blue and black nodes is sufficient.
whiteRectangle.physicsBody?.contactTestBitMask = blackCategory
whiteRectangle.physicsBody?.contactTestBitMask = blueCategory