Question

我一直遇到从其他类访问变量的问题。这是我的代码。这是我试图访问变量＆＃34; lastSelection＆＃34;它也是第一个被称为观看的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)
    }
}

每当打印出来时，它都会打印出＃34;＆＃34;。它应该是印刷＆＃34; Mustang＆＃34;。

Answer 1

在这一行：

FighterPlane = FighterPlaneSelect()

您实例化该类的新 SKScene。问题是，从未显示过这样的方法：永远不会调用func didMoveToView(view: SKView)。

您需要的是对另一个场景的引用。

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

您可以在场景的初始化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)  {

    }
}

然后就像你一样使用它：

class GameField : SKScene {
    var FighterPlane : FighterPlaneselect!

    override func didMoveToView(view: SKView) {


        FighterPlane = FighterPlaneselect(size: self.size)

        println(FighterPlane.lastSelection)
    }
}

Answer 3

非常简单！只需在课堂外声明lastSelection !!

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

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

}

如何在Swift SpriteKit中从另一个SKScene访问变量

3 个答案: