SKPhysics Contact not functioning properly - swift

Question

I am trying to use the SKPhysicsContactDelegate function in SpriteKit and it will not seem to work. I want one sprite to perform an action when it hits the other. I have set up breakpoints at the didBeginContact function and for some reason my application never calls this function. All help appreciated. Code posted below.
struct PhysicsCatagory {
static let Enemy :UInt32 = 0x1 << 0
static let Slider :UInt32 = 0x1 << 1
static let Circle :UInt32 = 0x1 << 2
}
class GameScene: SKScene, SKPhysicsContactDelegate {
var EnemyTimer = NSTimer()
var Circle = SKSpriteNode()
var Slider = SKSpriteNode()
var FastButton = SKNode()
var Title = SKSpriteNode()
var Text = SKSpriteNode()
var Path = UIBezierPath()
var gameStarted = Bool()
override func didMoveToView(view: SKView) {
self.physicsWorld.contactDelegate = self
self.backgroundColor = UIColor.whiteColor()
Circle = SKSpriteNode(imageNamed:"blueCircle")
Circle.size = CGSize(width: 140, height: 140)
Circle.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame))
Circle.zPosition = 1.0
self.addChild(Circle)
Slider = SKSpriteNode(imageNamed: "blocker1")
Slider.size = CGSize(width: 15, height: 50)
Slider.position = CGPoint(x: self.frame.width / 2, y: self.frame.height / 2 + 80)
addChild(Slider)
Slider.zPosition = 1.0
moveClockWise()
}
func didBeginContact(contact: SKPhysicsContact) {
if contact.bodyA.node != nil && contact.bodyB.node != nil{
let firstBody = contact.bodyA.node as! SKSpriteNode
let secondBody = contact.bodyB.node as! SKSpriteNode
if ((firstBody.name == "Enemy") && (secondBody.name == "Slider")){
collisionBall(firstBody, Slider: secondBody)
}
else if ((firstBody.name == "Slider") && (secondBody.name == "Enemy")) {
collisionBall(secondBody, Slider: firstBody)
}
}
}
func collisionBall(Enemy : SKSpriteNode, Slider : SKSpriteNode){
Enemy.physicsBody?.dynamic = true
Enemy.physicsBody?.affectedByGravity = true
Enemy.physicsBody?.mass = 4.0
Slider.physicsBody?.mass = 4.0
Enemy.removeAllActions()
Enemy.physicsBody?.contactTestBitMask = 0
Enemy.physicsBody?.collisionBitMask = 0
Enemy.name = nil
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
//Slider.hidden = false
FastButton.hidden = false
Title.hidden = true
Text.hidden = true
EnemyTimer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: #selector(GameScene.Enemies), userInfo: nil, repeats: true)
//Physics
Slider.physicsBody?.categoryBitMask = PhysicsCatagory.Slider
Slider.physicsBody?.collisionBitMask = PhysicsCatagory.Enemy
Slider.physicsBody?.contactTestBitMask = PhysicsCatagory.Enemy
Slider.name = "Slider"
Slider.physicsBody?.dynamic = true
Slider.physicsBody?.affectedByGravity = true
if gameStarted == false{
gameStarted = true
}
else if gameStarted == true{
}
}
func moveClockWise(){
let dx = Slider.position.x / 2
let dy = Slider.position.y / 2
let rad = atan2(dy, dx)
let Path = UIBezierPath(arcCenter: CGPoint(x: self.frame.width / 2, y: self.frame.height / 2), radius: 90, startAngle: rad, endAngle: rad + CGFloat(M_PI * 4), clockwise: true)
let follow = SKAction.followPath(Path.CGPath, asOffset: false, orientToPath: true, speed: 150)
//let rotate = SKAction.rotateByAngle(75, duration: 100)
Slider.runAction(SKAction.repeatActionForever(follow).reversedAction())
//Slider.runAction(SKAction.repeatActionForever(rotate).reversedAction())
}
func Enemies(){
let Enemy = SKSpriteNode(imageNamed: "darkRedDot")
Enemy.size = CGSize(width: 20, height: 20)
//Physics
Enemy.physicsBody = SKPhysicsBody(circleOfRadius: Enemy.size.width / 2)
Enemy.physicsBody?.categoryBitMask = PhysicsCatagory.Enemy
Enemy.physicsBody?.contactTestBitMask = PhysicsCatagory.Slider //| PhysicsCatagory.Circle
Enemy.physicsBody?.collisionBitMask = PhysicsCatagory.Slider //| PhysicsCatagory.Circle
Enemy.physicsBody?.dynamic = true
Enemy.physicsBody?.affectedByGravity = false
Enemy.name = "Enemy"

Answer 1

The contact is not beginning because your slider has no physics body, making it impossible to recognize contact. Unless, it's not in this code, your slider has no physics body, but your enemy does. Try declaring Slider.phisicsBody = SKPhysicsBody(texture: SKTexture(imageNamed: "blocker1"), size: Slider.size)
Also, you should read about standard naming conventions in Swift. It is recommended that your variables always start with lowercase letters (eg. enemyTimer, circle, slider, fastButton, etc...).