如何从Swift SpriteKit中的另一个SKScene访问变量

Question

我从其他类访问变量时遇到问题。 这是我的代码。 这是我正在尝试访问变量“ lastSelection”的类，这也是第一个调用来查看的SKScene。

class FighterPlaneselect : SKScene {
    var lastSelection:String = ""

    override func didMoveToView(view: SKView)  {
        if(true) {
            lastSelection = "Mustang"
        }
    }
}
//Here is the second class called "GameField"
class GameField : SKScene {
    var FighterPlane : FighterPlaneSelect!
    override func didMoveToView(view: SKView) {
        FighterPlane = FighterPlaneSelect()
        print(FighterPlane.lastSelection)
    }
}

无论何时打印出来，都会打印“”。 它应该打印“野马”。

Answer 1

在这行上：

FighterPlane = FighterPlaneSelect()

您实例化了该类的新 SKScene。 问题是，它从未显示，因此从未调用过func didMoveToView(view: SKView)方法。

您需要的是对其他场景的引用。

一种可能性是执行以下操作：

class FighterPlaneSelect : SKScene {
var lastSelection:String = ""

override func didMoveToView(view: SKView)  {
        if(true) {
            lastSelection = "Mustang"
        }
    }
}

//Here is the second class called "GameField"
class GameField : SKScene {
    var fighterPlane : FighterPlaneSelect!
    override func didMoveToView(view: SKView) {
        print(FighterPlane.lastSelection)
    }
}

//Here is in the GameScene
let fighterPlaneSelect = FighterPlaneSelect
//show the scene to make it move to view
//then assign the variable inside the gameField object
let gameField = GameField()
gameField.fighterPlane = fighterPlaneSelect

Answer 2

您可以在场景的init方法中初始化该变量：

  class FighterPlaneselect : SKScene {
    var lastSelection:String = ""

    override  init(size: CGSize){

        super.init(size: size)

         lastSelection = "Mustang"

    }

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

    override func didMoveToView(view: SKView)  {

    }
}

然后像现在一样使用它：

class GameField : SKScene {
    var FighterPlane : FighterPlaneselect!

    override func didMoveToView(view: SKView) {


        FighterPlane = FighterPlaneselect(size: self.size)

        println(FighterPlane.lastSelection)
    }
}

Answer 3

很简单！ 只需在类外声明lastSelection即可！！

class FighterPlaneselect : SKScene {
var lastSelection:String = "" //Declared in the class
}

var lastSelection:String = "" //Declared outside the class
class FighterPlaneselect : SKScene {

}