Swift - 必须调用超类 SKSpriteNode 错误的指定初始值设定项

Question

此代码在第一个 XCode 6 Beta 上工作，但在最新的 Beta 上它不起作用并出现此类错误Must call a designated initializer of the superclass SKSpriteNode ：

import SpriteKit

class Creature: SKSpriteNode {
  var isAlive:Bool = false {
    didSet {
        self.hidden = !isAlive
    }
  }
  var livingNeighbours:Int = 0

  init() {
    // throws: must call a designated initializer of the superclass SKSpriteNode
    super.init(imageNamed:"bubble") 
    self.hidden = true
  }

  init(texture: SKTexture!) {
    // throws: must call a designated initializer of the superclass SKSpriteNode
    super.init(texture: texture)
  }

  init(texture: SKTexture!, color: UIColor!, size: CGSize) {
    super.init(texture: texture, color: color, size: size)
  }
}

这就是这个类的初始化方式：

let creature = Creature()
creature.anchorPoint = CGPoint(x: 0, y: 0)
creature.position = CGPoint(x: Int(posX), y: Int(posY))
self.addChild(creature)

我被它困住了..最简单的解决方法是什么？

Answer 1

init(texture: SKTexture!, color: UIColor!, size: CGSize)是 SKSpriteNode 类中唯一的指定构造器，其余都是便利构造器，所以不能调用 super 。 将您的代码更改为：

class Creature: SKSpriteNode {
    var isAlive:Bool = false {
        didSet {
            self.hidden = !isAlive
        }
    }
    var livingNeighbours:Int = 0

    init() {
        // super.init(imageNamed:"bubble") You can't do this because you are not calling a designated initializer.
        let texture = SKTexture(imageNamed: "bubble")
        super.init(texture: texture, color: UIColor.clearColor(), size: texture.size())
        self.hidden = true
    }

    init(texture: SKTexture!) {
        //super.init(texture: texture) You can't do this because you are not calling a designated initializer.
        super.init(texture: texture, color: UIColor.clearColor(), size: texture.size())
    }

    init(texture: SKTexture!, color: UIColor!, size: CGSize) {
        super.init(texture: texture, color: color, size: size)
    }
}

此外，我会将所有这些合并到一个初始值设定项中。

Answer 2

疯狂的东西..我不完全明白我是如何设法修复它的..但这有效：

convenience init() {
    self.init(imageNamed:"bubble")
    self.hidden = true
}

init(texture: SKTexture!, color: UIColor!, size: CGSize) {
    super.init(texture: texture, color: color, size: size)
}

为init增加convenience并删除init(texture: SKTexture!)