SpriteKit（Swift）敌人没有被删除/敌人和子弹似乎没有联系

Question

import SpriteKit
import GameplayKit

class GameScene: SKScene, SKPhysicsContactDelegate {

    let player = SKSpriteNode(imageNamed: "Player")

    struct PhysicsCategories {
        static let None: UInt32 = 0
        static let Player: UInt32 = 0b1 //1
        static let Bullet: UInt32 = 0b10 //2
        static let Enemy: UInt32 = 0b100 //4
    }

    override func didMove(to view: SKView) {

        self.physicsWorld.contactDelegate = self

        player.setScale(0.2)
        player.position = CGPoint(x: self.size.width/2, y: self.size.height * 0.2)
        player.zPosition = 2
        player.physicsBody = SKPhysicsBody(rectangleOf: player.size)
        player.physicsBody!.affectedByGravity = false
        player.physicsBody!.categoryBitMask = PhysicsCategories.Player
        player.physicsBody!.collisionBitMask = PhysicsCategories.None
        player.physicsBody?.isDynamic = true
        player.physicsBody!.contactTestBitMask = PhysicsCategories.Enemy
        self.addChild(player)

    }


    func didBeginContact(contact: SKPhysicsContact) {
        var body1 = SKPhysicsBody()
        var body2 = SKPhysicsBody()

        if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
            body1 = contact.bodyA
            body2 = contact.bodyB
        }
        else {
            body1 = contact.bodyB
            body2 = contact.bodyA
        }

        if body1.categoryBitMask == PhysicsCategories.Player && body2.categoryBitMask == PhysicsCategories.Enemy {
            // if player hit enemy

            if body1.node != nil {

                spawnExplosion(spawnPosition: body1.node!.position)
            }

            if body2.node != nil {

                spawnExplosion(spawnPosition: body2.node!.position)
            }

            body1.node!.removeFromParent()
            body2.node!.removeFromParent()

        }

        if body1.categoryBitMask == PhysicsCategories.Bullet && body2.categoryBitMask == PhysicsCategories.Enemy {
            // if bullet hit enemy

            if body2.node != nil {
                if body2.node!.position.y > self.size.height {
                    return
                }
                else {
                    spawnExplosion(spawnPosition: body2.node!.position)
                }
            }

            body1.node!.removeFromParent()
            body2.node!.removeFromParent()

        }

    }

    func fireBullet()   {

        let bullet = SKSpriteNode(imageNamed: "Bullet")
        bullet.setScale(0.8)
        bullet.position = player.position
        bullet.zPosition = 1
        bullet.physicsBody = SKPhysicsBody(rectangleOf: bullet.size)
        bullet.physicsBody!.affectedByGravity = false
        bullet.physicsBody!.categoryBitMask = PhysicsCategories.Bullet
        bullet.physicsBody!.collisionBitMask = PhysicsCategories.None
        bullet.physicsBody?.isDynamic = true
        bullet.physicsBody!.contactTestBitMask = PhysicsCategories.Enemy
        self.addChild(bullet)

        let moveBullet = SKAction.moveTo(y: self.size.height + bullet.size.height, duration: 1)
        let deleteBullet = SKAction.removeFromParent()
        let bulletSequence = SKAction.sequence([bulletSound, moveBullet, deleteBullet])
        bullet.run(bulletSequence)
    }

    func spawnEnemy()

        let randomxStart = randomBetweenNumbers(firstNum: 0, secondNum: frame.width)
        let randomxEnd = randomBetweenNumbers(firstNum: 0, secondNum: frame.width)

        let startPoint = CGPoint(x: randomxStart, y: self.size.height * 1.2 )
        let endPoint = CGPoint(x: randomxEnd, y: -self.size.height * 0.2)

        let Enemy = SKSpriteNode(imageNamed: "EnemyShip")
        Enemy.setScale(0.2)
        Enemy.position = startPoint
        Enemy.zPosition = 2
        Enemy.physicsBody = SKPhysicsBody(rectangleOf: Enemy.size)
        Enemy.physicsBody!.affectedByGravity = false
        Enemy.physicsBody!.categoryBitMask = PhysicsCategories.Enemy
        Enemy.physicsBody!.collisionBitMask = PhysicsCategories.None
        Enemy.physicsBody?.isDynamic = true
        Enemy.physicsBody!.contactTestBitMask = PhysicsCategories.Player | PhysicsCategories.Bullet
        self.addChild(Enemy)

        let moveEnemy = SKAction.move(to: endPoint, duration: 1.5)
        let deleteEnemy = SKAction.removeFromParent()
        let enemySequence = SKAction.sequence([moveEnemy, deleteEnemy])
        Enemy.run(enemySequence)

        let dx = endPoint.x - startPoint.x
        let dy = endPoint.y - startPoint.y
        let amountToRotate = atan2(dy, dx)
        let degreesToRadians = CGFloat.pi / 180
        //  let radiansToDegree = 180 / CGFloat.pi
        Enemy.zRotation = amountToRotate - 90 * degreesToRadians

    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {

        fireBullet()
    }

}

所以我刚刚开始通过构建简单的游戏来学习 SpriteKit 和 Swift。代码是构建类似太空入侵者的游戏。我被困在代码的联系报告部分，其中子弹和敌人在接触时被删除/敌人和玩家在接触时被删除。

我已经设置了玩家、敌人、子弹的物理体。在类似问题上看到了一些 StackOverFlow 问题并输入 isDynamic = true。放入 ifBeginContact -> removeFromParent 但目前我不知道为什么，敌人在被子弹击中时不会被删除。我把基本代码留在里面了。请帮忙。

Answer 1

可能在评论中提到的另一个函数内部有一个函数。

添加了 view.ShowPhysics = true。将 func didBegin 移到了最底部，显然它起作用了。