currently I'm in project 17 where i have complete full project but the in last video of it there is use the didbegin but it is not working in me xcode and in ipad simulater

code:

//
//  GameScene.swift
//  project17
//
//  Created by Divyang Parmar on 02/09/23.
//

import SpriteKit

class GameScene: SKScene, SKPhysicsContactDelegate {
    var starFeild: SKEmitterNode!
    var player: SKSpriteNode!
    var scoreLabel: SKLabelNode!
    var score = 0 {
        didSet {
            scoreLabel.text = "Score \(score)"
        }
    }

    var possibleEnemies = ["ball", "hammer", "tv"]
    var gameTimer: Timer?
    var isGameOver = false

    override func didMove(to view: SKView) {
        backgroundColor = .black

        starFeild = SKEmitterNode(fileNamed: "starfield")!
        starFeild.position = CGPoint(x: 1024, y: 384)
        starFeild.advanceSimulationTime(10)
        starFeild.zPosition = -1
        addChild(starFeild)

        player = SKSpriteNode(imageNamed: "player")
        player.position = CGPoint(x: 100, y: 384)
        player.physicsBody = SKPhysicsBody(texture: player.texture!, size: player.size)
        player.physicsBody?.collisionBitMask = 1
        addChild(player)

        scoreLabel = SKLabelNode(fontNamed: "Chalkduster")
        scoreLabel.text = "Score \(score)"
        scoreLabel.horizontalAlignmentMode = .left
        scoreLabel.position = CGPoint(x: 15, y: 15)
        addChild(scoreLabel)

        physicsWorld.gravity = .zero
        physicsWorld.contactDelegate = self

        gameTimer = Timer.scheduledTimer(timeInterval: 0.35, target: self, selector: #selector(createEnemy), userInfo: nil, repeats: true)
    }

    override func update(_ currentTime: TimeInterval) {
        for node in children {
            if node.position.x < -300 {
                node.removeFromParent()
            }
        }

        if !isGameOver {
            score += 1
        }
    }

    @objc func createEnemy() {
        guard let enemy = possibleEnemies.randomElement() else { return }

        let sprit = SKSpriteNode(imageNamed: enemy)
        sprit.position = CGPoint(x: 1200, y: Int.random(in: 50...735))
        addChild(sprit)

        sprit.physicsBody = SKPhysicsBody(texture: sprit.texture!, size: sprit.size)
        sprit.physicsBody?.categoryBitMask = sprit.physicsBody?.collisionBitMask ?? 0
        sprit.physicsBody?.velocity = CGVector(dx: -500, dy: 0)
        sprit.physicsBody?.angularVelocity = 5
        sprit.physicsBody?.linearDamping = 0
        sprit.physicsBody?.angularDamping = 0
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        guard let touch = touches.first else { return }

        var location = touch.location(in: self)

        if location.y < 100 {
            location.y = 100
        } else if location.y > 668 {
            location.y = 668
        }

        player.position = location
    }

     func didBegin(_ contact: SKPhysicsContact) {
        let explosion = SKEmitterNode(fileNamed: "explosion")!
        explosion.position = player.position
        addChild(explosion)

        player.removeFromParent()
        isGameOver = true
    }

}

Hi! Here is the working code, so you can check what is missing or play around with it to find out why yours is not working.

class GameScene: SKScene, SKPhysicsContactDelegate {

  var starfield: SKEmitterNode!
  var player: SKSpriteNode!

  var scoreLabel: SKLabelNode!
  var score = 0 {
    didSet {
      scoreLabel.text = "Score: \(score)"
    }
  }

  let possibleEnemies = ["ball", "hammer", "tv"]
  var isGameOver = false
  var gameTimer: Timer?

  override func didMove(to view: SKView) {
    backgroundColor = .black

    starfield = SKEmitterNode(fileNamed: "starfield")
    starfield.position = CGPoint(x: 1024, y: 384)
    starfield.advanceSimulationTime(10)
    addChild(starfield)
    starfield.zPosition = -1

    player = SKSpriteNode(imageNamed: "player")
    player.position = CGPoint(x: 100, y: 384)
    player.physicsBody = SKPhysicsBody(texture: player.texture!, size: player.size)
    player.physicsBody?.contactTestBitMask = 1
    addChild(player)

    scoreLabel = SKLabelNode(fontNamed: "Chalkduster")
    scoreLabel.position = CGPoint(x: 16, y: 16)
    scoreLabel.horizontalAlignmentMode = .left
    addChild(scoreLabel)

    score = 0

    physicsWorld.gravity = .zero
    physicsWorld.contactDelegate = self

    gameTimer = Timer.scheduledTimer(timeInterval: 0.35, target: self, selector: #selector(createEnemy), userInfo: nil, repeats: true)

  }

  override func update(_ currentTime: TimeInterval) {
    for node in children {
      if node.position.x < -300 {
        node.removeFromParent()
      }
    }
    if !isGameOver {
      score += 1
    }
  }

  @objc func createEnemy() {
    guard let enemy = possibleEnemies.randomElement() else { return }

    let sprite = SKSpriteNode(imageNamed: enemy)
    sprite.position = CGPoint(x: 1200, y: Int.random(in: 50...736))
    addChild(sprite)

    sprite.physicsBody = SKPhysicsBody(texture: sprite.texture!, size: sprite.size)
    sprite.physicsBody?.categoryBitMask = 1
    sprite.physicsBody?.velocity = CGVector(dx: -500, dy: 0)
    sprite.physicsBody?.angularVelocity = 5
    sprite.physicsBody?.linearDamping = 0
    sprite.physicsBody?.angularDamping = 0
  }

  override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else { return }
    var location = touch.location(in: self)

    if location.y < 100 {
      location.y = 100
    } else if location.y > 668 {
      location.y = 668
    }

    player.position = location
  }

  func didBegin(_ contact: SKPhysicsContact) {
    let explosion = SKEmitterNode(fileNamed: "explosion")!
    explosion.position = player.position
    addChild(explosion)

    player.removeFromParent()
    isGameOver = true
  }
}