swift - 如何在多次点击时删除节点

Question

我正在制作一款太空入侵者游戏，其中有许多敌舰向您驶来，您必须向它们射击。

当玩家触摸屏幕时，玩家飞船会向敌舰发射子弹。

我明白了，每当一颗子弹碰到敌舰时，它就会从父舰上移除。但是我无法得到它，因此需要 2 颗子弹才能将敌舰从母舰上移走。出于某种原因，每当另一艘敌舰被召唤到现场时，敌人的生命就会自行重置。怎样才能让每艘敌舰都有自己独立的生命，并且不影响其他敌舰的生命？

这是敌人类:

public class Villain: SKSpriteNode {

var life = 2

init(){

    let texture = SKTexture(imageNamed: "Villain")
    var life = 2
    print("number of lives: ", life)
    super.init(texture: texture, color: SKColor.clear, size: texture.size())
    self.name = "villain"
}

required public init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

这里是调用Enemy类的GameScene类

func VillainRight(){
    let TooMuch = self.size.width
    let point = UInt32(TooMuch)

    let VillainR = Villain()

    VillainR.zPosition = 2
    VillainR.position = CGPoint(x: self.frame.minX,y: CGFloat(arc4random_uniform(point)))

    //This code makes the villain's Zposition point towards the SpaceShip
    let angle = atan2(SpaceShip.position.y - VillainR.position.y, SpaceShip.position.x - VillainR.position.x)
    VillainR.zRotation = angle - CGFloat(M_PI_2)

    let MoveToCenter = SKAction.move(to: CGPoint(x: self.frame.midX, y: self.frame.midY), duration: 15)

    //Physics World
    VillainR.physicsBody = SKPhysicsBody(rectangleOf: VillainR.size)
    VillainR.physicsBody?.categoryBitMask = NumberingPhysics.RightV
    VillainR.physicsBody?.contactTestBitMask = NumberingPhysics.Laser | NumberingPhysics.SpaceShip
    VillainR.physicsBody?.affectedByGravity = false
    VillainR.physicsBody?.isDynamic = true

    VillainR.run(MoveToCenter)
    addChild(VillainR)
}

这里是 didBeginContact 方法的一部分:

 //LASERS HIT ENEMY CHECK

    if BodyOne.categoryBitMask == NumberingPhysics.Laser && BodyTwo.categoryBitMask == NumberingPhysics.LeftV{
        run(VillainGone)
        ToNextLevel -= 1

        if BodyTwo.node != nil{
            MakeExplosions(BodyTwo.node!.position)
        }

        BodyTwo.node?.removeFromParent()
        BodyOne.node?.removeFromParent()
    }

    if BodyOne.categoryBitMask == NumberingPhysics.Laser && BodyTwo.categoryBitMask == NumberingPhysics.RightV{

        ToNextLevel -= 1

        if BodyTwo.node != nil{
            MakeExplosions(BodyTwo.node!.position)
        }

        run(VillainGone)
        BodyOne.node?.removeFromParent()
        BodyTwo.node?.removeFromParent()
    }
}

回顾:

我想要做的就是让敌舰在 2 颗子弹碰到它时从 Parent 中移除。并且敌方生命相互独立(如果一艘敌舰还剩下 1 条生命，那么如果另一艘敌舰被召唤到现场，它不会重置回 2)。

Answer 1

这是您问题的示例解决方案(这是一个 macOS 项目，如果您要转换，只需将 mouseDown 替换为 touchesBegan)。

点击屏幕观看反派生命值耗尽，当达到 0 时反派将死亡并从场景中移除:

let category1 = UInt32(1)
let category2 = UInt32(2)


class Villain: SKSpriteNode {

  var lives = 2
  var hitThisFrame = false

  init(color: SKColor, size: CGSize) {
    super.init(texture: nil, color: color, size: size)
    let pb = SKPhysicsBody(rectangleOf: self.size)
    pb.categoryBitMask = category1
    pb.contactTestBitMask = category2
    self.physicsBody = pb
  }

  required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }
}

class Hero: SKSpriteNode {

  init(color: SKColor, size: CGSize) {
    super.init(texture: nil, color: color, size: size)
    let pb = SKPhysicsBody(rectangleOf: self.size)
    pb.categoryBitMask = category2
    pb.contactTestBitMask = category1
    self.physicsBody = pb
  }
  required init?(coder aDecoder: NSCoder) { fatalError() }
}


class GameScene: SKScene, SKPhysicsContactDelegate {

  let villain = Villain(color: .blue,  size: CGSize(width: 50, height: 50))
  let hero    = Hero   (color: .green, size: CGSize(width: 50, height: 50))

  override func didMove(to view: SKView) {
    physicsWorld.contactDelegate = self
    physicsWorld.gravity = CGVector.zero

    hero.position.y -= 100
    addChild(villain)
    addChild(hero)
  }

  func didBegin(_ contact: SKPhysicsContact) {
    let contactedBodies = contact.bodyA.categoryBitMask + contact.bodyB.categoryBitMask

    if contactedBodies == category1 + category2 {

      // Find which one of our contacted nodes is a villain:
      var vil: Villain
      if let foundVil = contact.bodyA.node as? Villain {
        vil = foundVil
      } else if let foundVil = contact.bodyB.node as? Villain {
        vil = foundVil
      } else {
        fatalError("one of the two nodes must be a villain!!")
      }


      if vil.hitThisFrame {
        // Ignore a second contact if already hit this frame:
        return
      } else {
        // Damage villain:
        vil.lives -= 1
        print(" vil lives: \(vil.lives)")
        vil.hitThisFrame = true
        if vil.lives == 0 {
          // Kill villain:
          print("villain is dead!!!")
          vil.physicsBody = nil
          vil.removeFromParent()
        }
      }
    }
  }

  override func didSimulatePhysics() {
    // Reset hero position (so as to not trigger another didBegin()
    hero.position = CGPoint(x: 0, y: -100)
    // Allow villain to be hit again next frame:
    villain.hitThisFrame = false
  }
  override func mouseDown(with event: NSEvent) {
    // Trigger didBegin():
    hero.position = villain.position
  }
}