无法使用 unarchiveFromFile 在 SpriteKit 中设置 GameScene

Question

我正在使用 Xcode 7 beta 2 并按照 raywenderlich.com 的 Breakout 教程来学习 SpriteKit。这是我尝试使用 unarchiveFromFile 加载 GameScene 时遇到的错误。

GameScene.type does not have a member named unarchiveFromFile.

代码如下：

func didBeginContact(contact: SKPhysicsContact) {
    // 1. Create local variables for two physics bodies
    var firstBody: SKPhysicsBody
    var secondBody: SKPhysicsBody

    // 2. Assign the two physics bodies so that the one with the lower category is always stored in firstBody
    if contact.bodyA.categoryBitMask < contact.bodyB.categoryBitMask {
        firstBody = contact.bodyA
        secondBody = contact.bodyB
    } else {
        firstBody = contact.bodyB
        secondBody = contact.bodyA
    }

    // 3. react to the contact between ball and bottom
    if firstBody.categoryBitMask == BallCategory && secondBody.categoryBitMask == BottomCategory {
        //TODO: Replace the log statement with display of Game Over Scene

        if let mainView = view {
            let gameOverScene = GameOverScene.unarchiveFromFile("GameOverScene") as! GameOverScene
            gameOverScene.gameWon = false
            mainView.presentScene(gameOverScene)
        }
    }
}

Answer 1

您应该使用 init(fileNamed:) 初始化器，它从 iOS 8 开始可用。例如：

if let gameOverScene = GameOverScene(fileNamed: "GameOverScene") {
    // ...
}

重要的是要注意 init(fileNamed:) 是 SKNode 上的便利初始化程序：

convenience init?(fileNamed filename: String)

因此，GameOverScene要自动继承init(fileNamed:)，GameOverScene必须遵守The Swift Programming Language: Initialisation的以下规则（特别是规则 2):

Assuming that you provide default values for any new properties you introduce in a subclass, the following two rules apply:

Rule 1 If your subclass doesn’t define any designated initializers, it automatically inherits all of its superclass designated initializers.

Rule 2 If your subclass provides an implementation of all of its superclass designated initializers—either by inheriting them as per rule 1, or by providing a custom implementation as part of its definition—then it automatically inherits all of the superclass convenience initializers.

无法使用 unarchiveFromFile 在 SpriteKit 中设置 GameScene

Cannot use unarchiveFromFile to set GameScene in SpriteKit

sprite-kit

swift

xcode7-beta2