sprite-kit - 错误 : "Property ' self. gameArea' 未在 super.init 调用中初始化”

Question

我收到标题中写的错误。我对这一切都很陌生。任何帮助表示赞赏。

这是 GameScene.swift 文件:

class GameScene: SKScene {

let player = SKSpriteNode(imageNamed: "shuttle")

let bulletSound = SKAction.playSoundFileNamed("torpedo.mp3", waitForCompletion: false)

let gameArea: CGRect

override init(size: CGSize) {

    let maxRatio: CGFloat = 16.0/9.0
    let playableWidth = size.height / maxRatio
    let margin = (size.width - playableWidth) / 2

    gameArea = CGRect(x: margin - size.width / 2, y: size.height / 2, width: playableWidth, height: size.height)

    super.init(size: size)

}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

Answer 1

我建议你阅读 initialization process . Swift 执行两步初始化。第一阶段是初始化所有存储的属性。此外，Swift 编译器执行很少的安全检查以确保正确执行两阶段初始化。这是来自文档:

Safety check 1

A designated initializer must ensure that all of the properties introduced by its class are initialized before it delegates up to a superclass initializer.

因此，您可以在初始化程序中初始化您的属性:

required init?(coder aDecoder: NSCoder) {
        self.gameArea = CGRect()
        super.init(coder: aDecoder)
    }

或在属性声明(并可选择将其声明为 var):

var gameArea = CGRect()

如果您不将其设为 var，则在初始化后(在声明时)您将无法在以后更改它。在初始化程序中初始化属性时也是如此。如果它是一个 let 常量，则不可能进行进一步的修改。