从 NSUserDefaults 更改为 NSCoding

Question

我正在尝试创建我的第一个 sprite kit swift 游戏，并且我的游戏数据使用 nsuserdefaults 工作。我想让它更安全，所以我试图过渡到 NSCoding，但我在网上找到的任何东西都没有完全帮助我，只是让我感到困惑（如果答案已经存在，很抱歉，我可能已经看过它并且是'无法理解。）

这是我的 GameState 类：

class GameState {
var score: Int
var highScore: Int
var stars: Int
var sound: Bool
var carType: Int
var xSize: Double
var ySize: Double
var gameOver: Bool

class var sharedInstance: GameState {
    struct Singleton {
        static let instance = GameState()
    }

    return Singleton.instance
}

init() {
    // Init
    score = 0
    highScore = 0
    stars = 0
    carType = 1
    sound = true
    xSize = 1
    ySize = 1
    gameOver = false

    // Load game state
    let defaults = NSUserDefaults.standardUserDefaults()

    highScore = defaults.integerForKey("highScore")
    stars = defaults.integerForKey("stars")
    sound = defaults.boolForKey("sound")
    carType = defaults.integerForKey("carType")
    xSize = defaults.doubleForKey("xSize")
    ySize = defaults.doubleForKey("ySize")
    gameOver = defaults.boolForKey("gameOver")
}


func saveState() {
    // Update highScore if the current score is greater
    highScore = max(score, highScore)

    // Store in user defaults
    let defaults = NSUserDefaults.standardUserDefaults()
    defaults.setInteger(highScore, forKey: "highScore")
    defaults.setInteger(stars, forKey: "stars")
    defaults.setBool(sound, forKey: "sound")
    defaults.setInteger(carType, forKey: "carType")
    defaults.setDouble(xSize, forKey: "xSize")
    defaults.setDouble(ySize, forKey: "ySize")
    defaults.setBool(gameOver, forKey: "gameOver")
    NSUserDefaults.standardUserDefaults().synchronize()
} }

我使用以下方法在其他类中保存和加载数据：

GameState.sharedInstance.*****

我将如何更改它以实现 NSCoding，然后从其他类加载和保存数据？谢谢。

Answer 1

您要保存的类必须符合NSCoding 协议并实现required init(coder aDecoder: NSCoder) 和func encodeWithCoder(aCoder: NSCoder)。

这是一个简化的例子：

class GameState: NSObject, NSCoding {

    var score: Int?
    var gameOver: Bool?

    init(score: Int, gameOver: Bool) {
        super.init()
        self.score = score
        self.gameOver = gameOver
    }

    required init(coder aDecoder: NSCoder) {
        self.score = aDecoder.decodeObjectForKey("score") as? Int
        self.gameOver = aDecoder.decodeObjectForKey("gameOver") as? Bool
    }

    func encodeWithCoder(aCoder: NSCoder) {
        aCoder.encodeObject(self.score, forKey: "score")
        aCoder.encodeObject(self.gameOver, forKey: "gameOver")
    }

}

let myGameState = GameState(score: 42, gameOver: true)

然后您可以使用NSKeyedArchiver 和NSKeyedUnarchiver，例如在 AppDelegate 中，将您的对象作为数据保存和加载：

func applicationWillTerminate(aNotification: NSNotification) {
    NSKeyedArchiver.archiveRootObject(myGameState, toFile: "a/file/path")
}

func applicationDidFinishLaunching(aNotification: NSNotification) {
    if let data = NSKeyedUnarchiver.unarchiveObjectWithFile("a/file/path") as? GameState {
        myGameState = data
    }
}