Question

我正在制作一个简单的iOS游戏，但遇到一些问题。实际上，我为元素创建了不同的类：行星，子弹头，背景和小行星。但是，当我尝试在切换条件下（从GameScene）初始化它们时，出现错误消息“期望的声明”。

变量“ lvlSelected”是全局变量，代表玩家（从另一个场景）要求的级别。

这是我的切换代码：

 switch lvlSelected {
case 1 :
private var planet = Planet(imageName: "Planet1")
private var bullet = Bullet(imageName: "Bullet1")
private var background = Background(imageName: "Background1")
private var asteroide = Asteroides(img: "Asteroid1")

case 2 :
private var planet = Planet(imageName: "Planet2")
private var bullet = Bullet(imageName: "Bullet2")
private var background = Background(imageName: "Background2")
private var asteroide = Asteroides(img: "Asteroid2")

default :
private var planet = Planet(imageName: "Planet")
private var bullet = Bullet (imageName: "Bullet")
private var background = Background(imageName : "Background")
private var asteroide = Asteroides(img."Asteroid")
}

感谢您的帮助

这是我星球的课程：

class Planet:SKSpriteNode {

init(imageName: String){

    let texture = SKTexture(imageNamed : imageName)
    super.init(texture: texture, color: .clear, size: texture.size())

    self.physicsBody = SKPhysicsBody(circleOfRadius: self.size.width/2, center: self.anchorPoint) 
    self.physicsBody!.affectedByGravity = false 
    self.physicsBody!.categoryBitMask = GameScene.physicsCategories.planet
    self.physicsBody!.collisionBitMask = GameScene.physicsCategories.none
    self.physicsBody!.contactTestBitMask = GameScene.physicsCategories.asteroid

}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}
 func addPlanet(parent: GameScene) {
    self.setScale(0.55)
    self.position = CGPoint(x: parent.size.width / 2, y: -self.size.height)
    self.zPosition = 2
    self.anchorPoint = CGPoint(x: 0.5, y: 0.5)
    parent.addChild(self)
}

Answer 1

这应该是您想要的方式。

private var planet = Planet(imageName: "Planet")
private var bullet = Bullet (imageName: "Bullet")
private var background = Background(imageName : "Background")
private var asteroide = Asteroides(img."Asteroid")

switch lvlSelected {
case 1 :
  planet = Planet(imageName: "Planet1")
  bullet = Bullet(imageName: "Bullet1")
  background = Background(imageName: "Background1")
  asteroide = Asteroides(img: "Asteroid1")
break
case 2 :
  planet = Planet(imageName: "Planet2")
  bullet = Bullet(imageName: "Bullet2")
  background = Background(imageName: "Background2")
  asteroide = Asteroides(img: "Asteroid2")
  break
default :
  break
}

如果您在switch case中声明var，则仅在该case中可用。

Answer 2

您的情况无需切换，可以使用字符串插值：

class GameScene : SKScene
{
    private let planet : Planet
    private let bullet : Bullet
    private let background : Background
    private let asteroide : Asteroides
    convenience init(lvlSelected : Int){

        let level = 1 ... 2 ~= lvlSelected ? "\(lvlSelected)" : ""
        planet = Planet(imageName: "Planet\(level)")
        bullet = Bullet (imageName: "Bullet\(level)")
        background = Background(imageName: "Background\(level)")
        asteroid = Asteroides(img: "Asteroid\(level)")
        self.init() //whatever init you use here
    }
}

~=是模式匹配运算符，#a ... #b表示a和b之间的数字范围，包括a和b，因此您要询问数字是否在一定范围内

(condition) ? (statement 1) : (statement 2)是三元运算符，如果条件为真，则为语句1否则为语句2

"\(var)"是字符串内插，告诉字符串将var的值注入字符串

在切换条件下加载一些私有变量

2 个答案: