Contact Delegate missing - swift

Question

I am trying to make a new level for my app. I am honestly just copy and pasting my code from the view controllers and gamescenes to other files that I changed the name of. Yes, I did change the names INSIDE the files too so It'll match the new level. However, my contact delegate won't work on my new level now. How can I fix this?
Cannot assign value of type 'Level1' to type 'SKPhysicsContactDelegate?'
What am I doing wrong? I just checked my main file that I had before creating a new level and it now has errors. I have't changed any of the coding.
import SpriteKit
import GameplayKit
class Level1: SKScene {
var ball = SKSpriteNode()
var danger1 = SKSpriteNode()
var danger2 = SKSpriteNode()
var goal = SKSpriteNode()
over
ride func didMove(to view: SKView) {
physicsWorld.contactDelegate = self
ball = self.childNode(withName: "ball") as! SKSpriteNode
danger1 = self.childNode(withName: "danger1") as! SKSpriteNode
danger2 = self.childNode(withName: "danger2") as! SKSpriteNode
goal = self.childNode(withName: "goal") as! SKSpriteNode
let border = SKPhysicsBody(edgeLoopFrom: self.frame)
border.friction = 0
border.restitution = 0
danger1.physicsBody = SKPhysicsBody(rectangleOf: danger1.size)
danger1.physicsBody?.categoryBitMask = PhysicsCategories.dangerCategory
danger1.physicsBody?.isDynamic = false
danger2.physicsBody = SKPhysicsBody(rectangleOf: danger2.size)
danger2.physicsBody?.categoryBitMask = PhysicsCategories.dangerCategory
danger2.physicsBody?.isDynamic = false
ball.physicsBody = SKPhysicsBody(circleOfRadius: ball.size.width/2)
ball.physicsBody?.categoryBitMask = PhysicsCategories.ballCategory
ball.physicsBody?.contactTestBitMask = PhysicsCategories.dangerCategory | PhysicsCategories.goalCategory
ball.physicsBody?.collisionBitMask = PhysicsCategories.none
ball.physicsBody?.isDynamic = true
ball.physicsBody!.affectedByGravity = false
goal.physicsBody = SKPhysicsBody(rectangleOf: goal.size)
goal.physicsBody?.categoryBitMask = PhysicsCategories.goalCategory
goal.physicsBody?.isDynamic = false
setupPhysics()
startGame()
}
func setupPhysics() {
physicsWorld.gravity = CGVector(dx: 0.0, dy: 0.0)
physicsWorld.contactDelegate = self
}
func startGame() {
ball.position = CGPoint(x: 0, y: 550)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
}
}
override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let location = touch.location(in: self)
ball.position.x = location.x
ball.position.y = location.y
}
}
override func update(_ currentTime: TimeInterval) {
// Called before each frame is rendered
}
}
extension GameScene: SKPhysicsContactDelegate {
func didBegin(_ contact: SKPhysicsContact) {
let contactMask = contact.bodyA.categoryBitMask | contact.bodyB.categoryBitMask
if contactMask == PhysicsCategories.ballCategory | PhysicsCategories.dangerCategory {
print("Contact")
} else if contactMask == PhysicsCategories.ballCategory | PhysicsCategories.goalCategory {
print("goal contact")
}
}
}

Answer 1

Instead of creating extension of GameScene, create extension of Level1
extension Level1: SKPhysicsContactDelegate