Question

在我与Swift一起开发的游戏中，我希望玩家能够在类似商店的场景中选择背景，从而改变每个SKScene的背景。我尝试使用UserDefaults来完成此操作，但由于某种原因它无法正常工作。这是商店场景的重要代码（我删除了不相关的代码）：

import SpriteKit

class ShopScene: SKScene {

var backNumber = 90
var backRemainder = 0
var background = SKSpriteNode()
var backName:String = "back1"

override func didMove(to view: SKView) {

    background.texture = SKTexture(imageNamed: "\(backName)")
    background.size = self.size
    self.addChild(background)

    let nextButton: NButton = NButton(defaultButtonImage: "next", activeButtonImage: "nextP", buttonAction: nextAction)
    addChild(nextButton)

    let selectButton: SButton = SButton(defaultButtonImage: "next", activeButtonImage: "nextP", buttonAction: selectAction)
    addChild(selectButton)   
}

func selectAction() {

    UserDefaults.standard.set(backName, forKey: "backSaved")

    let sceneToMoveTo = MainMenuScene(size: self.size)
    sceneToMoveTo.scaleMode = self.scaleMode
    let sceneTransition = SKTransition.fade(withDuration: 0.4)
    self.view!.presentScene(sceneToMoveTo, transition: sceneTransition)   
}

func nextAction() {

    backNumber += 1
    backRemainder = backNumber % 3

    switch backRemainder {
    case 0:
        backName = "back1"
    case 1:
        backName = "back2"
    case 2:
        backName = "back3"
    default:
        backName = "back1"
    }

    background.texture = SKTexture(imageNamed: "\(backName)")
}
}

如您所见，当按下选择按钮时，将保存名称。现在，这是主菜单场景的相关代码：

Import SpriteKit

class MainMenuScene: SKScene {

var backName = UserDefaults.standard.string(forKey: "backSaved")

override func didMove(to view: SKView) {

    let background = SKSpriteNode(imageNamed: "\(backName)")
    background.size = self.size
    self.addChild(background)

当选择＆＃39;按下按钮，您应该转换到主菜单场景，并看到背景是您选择的背景。但是，当我运行它时，我在白色背景中得到一个红色的X.我之前曾在UserDefaults工作过以节省分数，但我无法弄清楚为什么它在这种情况下不起作用。有关如何使用UserDefaults在SKScenes之间传递字符串的任何想法？我做错了吗？

注意：虽然Knight0fDragon的答案标记正确，但他的答案适用于在场景之间传递字符串，但不能永久保存该值。如果您希望传递该值并保存，请检查我的答案。

Answer 1

我建议不要执行UserDefaults，这是针对您的应用程序的首选项。而是使用userData

func selectAction() {

    let sceneToMoveTo = MainMenuScene(size: self.size)
    sceneToMoveTo.scaleMode = self.scaleMode
    sceneToMoveTo.userData = sceneToMoveTo.userData ?? NSMutableDictionary() //This lets us ensure userdata exists
    sceneToMoveTo.userData!["backSaved"] = backName
    let sceneTransition = SKTransition.fade(withDuration: 0.4)
    self.view!.presentScene(sceneToMoveTo, transition: sceneTransition)   
}

然后用：

实现它

import SpriteKit

class MainMenuScene: SKScene {



lazy var backName:String = {return self.userData?["backSaved"] as? String ?? "back1"}() //This allows us to load backName at the time it is needed, or assign back1 if doesn't exist

override func didMove(to view: SKView) {


    let background = SKSpriteNode(imageNamed: backName)
    self.addChild(background)

注意，我不确定是否如此？需要字符串，没有它就可以尝试，看看Swift是否可以推断它

Answer 2

显然，backName表现为可选，因为它没有值，因此为零。为了使我的代码工作，我对Shop Scene进行了这些更改：

import SpriteKit

class ShopScene: SKScene {

var backName:String? = UserDefaults.standard.string(forKey: "backSaved")

override func didMove(to view: SKView) {

    if backName != nil {
        backName = UserDefaults.standard.string(forKey: "backSaved")
    } else {
        backName = "back1"
    }

    background.texture = SKTexture(imageNamed: "\(backName!)")
    self.addChild(background)

并对主菜单场景进行了这些更改：

import SpriteKit

class MainMenuScene: SKScene {

var backName:String? = UserDefaults.standard.string(forKey: "backSaved")

override func didMove(to view: SKView) {

    if backName != nil {
        backName = UserDefaults.standard.string(forKey: "backSaved")
    } else {
        backName = "back1"
    }

    let background = SKSpriteNode(imageNamed: "\(backName!)")
    self.addChild(background)

使用UserDefaults

2 个答案: