Cannot assign PhysicsBody and property to an SKSpriteNode? - swift

Question

I'm building a function in which a random variable will choose 1 in 4 SKSpritenode in an array and assign itself to it. However, that randomline, although appear as expected on the screen, does not contain any physicsbody property so it cannot be collide with other node. Below is my code:
func line() {
redLine = SKSpriteNode(imageNamed: "redline")
blueLine = SKSpriteNode(imageNamed: "blueline")
yellowLine = SKSpriteNode(imageNamed: "yellowline")
greenLine = SKSpriteNode(imageNamed: "greenline")
let lineArray = [redLine,blueLine,yellowLine,greenLine]
// Add physics
lineArray[0].physicsBody?.categoryBitMask = gamePhysics.RedLine
lineArray[1].physicsBody?.categoryBitMask = gamePhysics.BlueLine
lineArray[2].physicsBody?.categoryBitMask = gamePhysics.YellowLine
lineArray[3].physicsBody?.categoryBitMask = gamePhysics.GreenLine
for i in 0...3 {
lineArray[i].physicsBody = SKPhysicsBody(circleOfRadius: 10)
lineArray[i].physicsBody?.collisionBitMask = gamePhysics.RedBall | gamePhysics.BlueBall | gamePhysics.YellowBall | gamePhysics.GreenBall
lineArray[i].physicsBody?.contactTestBitMask = gamePhysics.RedBall | gamePhysics.BlueBall | gamePhysics.YellowBall | gamePhysics.GreenBall
lineArray[i].physicsBody?.affectedByGravity = false
lineArray[i].physicsBody?.isDynamic = true
}
let randomLine:SKSpriteNode! = lineArray.randomElement()
...
self.addChild(randomLine)
...
randomLine.run(SKAction.sequence([moveLine,delay,removeLine]))
}
So basically when the randomline collide with other node, nothing happen.
Here is my didBegin (contact) func:
func didBegin(_ contact: SKPhysicsContact) {
let firstBody = contact.bodyA
let secondBody = contact.bodyB
if firstBody.categoryBitMask == gamePhysics.RedBall && secondBody.categoryBitMask == gamePhysics.RedLine || firstBody.categoryBitMask == gamePhysics.BlueBall && secondBody.categoryBitMask == gamePhysics.BlueLine || firstBody.categoryBitMask == gamePhysics.YellowBall && secondBody.categoryBitMask == gamePhysics.YellowLine || firstBody.categoryBitMask == gamePhysics.GreenBall && secondBody.categoryBitMask == gamePhysics.GreenLine {
currentScore += 1
secondBody.node?.removeFromParent()
print("hit point")
} else if firstBody.categoryBitMask == gamePhysics.RedLine && secondBody.categoryBitMask == gamePhysics.RedBall || firstBody.categoryBitMask == gamePhysics.BlueLine && secondBody.categoryBitMask == gamePhysics.BlueBall || firstBody.categoryBitMask == gamePhysics.YellowLine && secondBody.categoryBitMask == gamePhysics.YellowBall || firstBody.categoryBitMask == gamePhysics.GreenLine && secondBody.categoryBitMask == gamePhysics.GreenBall {
currentScore += 1
firstBody.node?.removeFromParent()
print("hit point")
}
}
Any help would be appreciated!
EDIT: Here is the ball func(). Maybe somehow the SKNode contain multiple categorybitmask and therefore, won't work?
func Ball() {
ballNode = SKNode()
redBall = SKSpriteNode(imageNamed: "redball")
blueBall = SKSpriteNode(imageNamed: "blueball")
yellowBall = SKSpriteNode(imageNamed: "yellowball")
greenBall = SKSpriteNode(imageNamed: "greenball")
let ballArray = [redBall,blueBall,yellowBall,greenBall]
...
// Add physics
ballArray[0].physicsBody?.categoryBitMask = gamePhysics.RedBall
ballArray[1].physicsBody?.categoryBitMask = gamePhysics.BlueBall
ballArray[2].physicsBody?.categoryBitMask = gamePhysics.YellowBall
ballArray[3].physicsBody?.categoryBitMask = gamePhysics.GreenBall
for i in 0...3 {
ballArray[i].physicsBody = SKPhysicsBody(circleOfRadius: 20)
ballArray[i].physicsBody?.collisionBitMask = gamePhysics.RedLine | gamePhysics.BlueLine | gamePhysics.YellowLine | gamePhysics.GreenLine
ballArray[i].physicsBody?.contactTestBitMask = gamePhysics.RedLine | gamePhysics.BlueLine | gamePhysics.YellowLine | gamePhysics.GreenLine
ballArray[i].physicsBody?.affectedByGravity = false
ballArray[i].physicsBody?.isDynamic = false
}
ballNode.addChild(redBall)
ballNode.addChild(greenBall)
ballNode.addChild(yellowBall)
ballNode.addChild(blueBall)
self.addChild(ballNode)
}
UPDATE 2:
Here is a struct where i store my categorybitmask:
struct gamePhysics {
static let RedBall : UInt32 = 0x1 << 1
static let BlueBall : UInt32 = 0x1 << 2
static let GreenBall : UInt32 = 0x1 << 3
static let YellowBall : UInt32 = 0x1 << 4
static let RedLine : UInt32 = 0x1 << 5
static let BlueLine : UInt32 = 0x1 << 6
static let GreenLine : UInt32 = 0x1 << 7
static let YellowLine : UInt32 = 0x1 << 8
}

Answer 1

Did you remember setting the contact delegate inside your scene? Place this line of code inside didMove(to:):
self.physicsWorld.contactDelegate = self
If this don't solve the issue, I would make the if conditions inside didBegin more explicit using parentheses between the && and || statements.
Looking to the rest of the code I can not see what else could be wrong, what you did should work. Are the print("hit point") you placed inside the if statements been reached?

Answer 2

OMG i found the answer to my question. The reason for the value of the categorybitmask to return "nil" was because i actually assign the node to categorybitmask before specified its physicsbody. Move the line down a few line and everything is solved!