Collision tests not working in SpriteKit Swift 2 - sprite-kit

Question

I have been trying to figure out why my didBeginContact method isn't working. I have a triangle falling from the top of the screen to the bottom and I have a line at the bottom which if it collides with it. My score should increment.
Here is the code responsible for this.
func createScene(){
physicsWorld.contactDelegate = self
slider = SKSpriteNode(imageNamed: "Slider")
slider.setScale(0.20)
slider.position = CGPoint(x: self.frame.width / 2, y: 0 + slider.frame.height / 2)
slider.physicsBody = SKPhysicsBody(rectangleOfSize: slider.size)
slider.physicsBody?.categoryBitMask = PhysicsCatergory.slider
slider.physicsBody?.collisionBitMask = PhysicsCatergory.coin | PhysicsCatergory.greenTriangle | PhysicsCatergory.orangeHexagon | PhysicsCatergory.purpleOctagon | PhysicsCatergory.redSquare
slider.physicsBody?.contactTestBitMask = PhysicsCatergory.coin | PhysicsCatergory.greenTriangle | PhysicsCatergory.orangeHexagon | PhysicsCatergory.purpleOctagon | PhysicsCatergory.redSquare
slider.physicsBody?.affectedByGravity = false
slider.physicsBody?.dynamic = false
var timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: Selector("SpawnShapes"), userInfo: nil, repeats: true)
self.addChild(slider)
}
func didBeginContact(contact: SKPhysicsContact) {
let firstBody = contact.bodyA
let secondBody = contact.bodyB
if firstBody.categoryBitMask == PhysicsCatergory.greenTriangle && secondBody.categoryBitMask == PhysicsCatergory.Score{
score++
print(score)
}
else if firstBody.categoryBitMask == PhysicsCatergory.Score && secondBody.categoryBitMask == PhysicsCatergory.greenTriangle{
score++
print(score)
}
}
override func didMoveToView(view: SKView) {
createScene()
invisibleBounderies()
}
func invisibleBounderies(){
let scoreNode = SKSpriteNode()
scoreNode.size = CGSize(width: 5, height: 600)
scoreNode.position = CGPoint(x: self.frame.width / 2, y: self.frame.height / 10)
scoreNode.physicsBody = SKPhysicsBody(rectangleOfSize: scoreNode.size)
scoreNode.physicsBody?.affectedByGravity = false
scoreNode.physicsBody?.dynamic = false
scoreNode.physicsBody?.categoryBitMask = PhysicsCatergory.Score
scoreNode.physicsBody?.collisionBitMask = PhysicsCatergory.greenTriangle
scoreNode.physicsBody?.contactTestBitMask = PhysicsCatergory.greenTriangle
scoreNode.zRotation = CGFloat(M_PI/2.0)
scoreNode.color = SKColor.blueColor()
self.addChild(scoreNode)
}
func SpawnShapes(){
greenTriangle = SKSpriteNode(imageNamed:"greenTriangle")
purpleOctagon = SKSpriteNode(imageNamed: "purpleOctagon")
redSquare = SKSpriteNode(imageNamed: "redSquare")
coin = SKSpriteNode(imageNamed: "coin")
greenTriangle.physicsBody = SKPhysicsBody(rectangleOfSize: greenTriangle.size)
greenTriangle.physicsBody?.categoryBitMask = 0
greenTriangle.physicsBody?.collisionBitMask = PhysicsCatergory.Score
greenTriangle.physicsBody?.contactTestBitMask = PhysicsCatergory.Score
greenTriangle.physicsBody?.affectedByGravity = false
greenTriangle.physicsBody?.dynamic = false
var MinValue = self.size.width / 8
var MaxValue = self.size.width - 150
var SpawnPoint = UInt32(MaxValue - MinValue)
let action = SKAction.moveToY(-30, duration: 2.0)
slider.zPosition = 1
coin.zPosition = 2
greenTriangle.zPosition = 3
orangeHexagon.zPosition = 4
purpleOctagon.zPosition = 5
redSquare.zPosition = 6
greenTriangle.position = CGPoint(x: CGFloat(arc4random_uniform(SpawnPoint)), y: self.size.height)
self.addChild(greenTriangle)
greenTriangle.runAction(SKAction.repeatActionForever(action))
}

Answer 1

You need to set only greenTriangle dynamic property to true.
You set greenTriangle.physicsBody?.categoryBitMask = 0, that's why you are not detecting contact. greenTriangle.physicsBody?.categoryBitMask = PhysicsCatergory.greenTriangle might do the trick.
If you are still not detecting contact after these changes, check if your physicsCatergory is alright. It would be good to implement an enum of type UInt32 where the values are all single bits, or like this, if you prefer:
enum PhysicsCatergory : UInt32{
case slider = 1
case coin = 2
case greenTriangle = 4
case purpleOctagon = 8
case redSquare = 16
case orangeHexagon = 32
case Score = 64
}
Doing like this will require to add .rawValue in every reference to one of these enums. Example: greenTriangle.physicsBody?.categoryBitMask = PhysicsCatergory.greenTriangle.rawValue
I know it is not related to the question, but I would recommend you not to use SKAction for movement in this case, because it's going to ignore physics collision, since you are "forcing" its position. Use the physicsBody.velocity property instead to let the physics work. You will notice that when using the later the block is going to collide with the score line, since you also set its collisionBitMask. This way you can properly control with that it collides. Set physicsBody.linearDamping to zero if don't want the block to lose speed while it travels (air friction).

Answer 2

A physicsBody with a dynamic property of false cannot be involved in collisions; set dynamic to true.