转自

• Swift设计模式

原文

• Design-Patterns-In-Swift

// 备忘录模式
// 百度百科：在不破坏封闭的前提下，捕获一个对象的内部状态，并在该对象之外保存这个状态。这样以后就可将该对象恢复到原先保存的状态
// 设计模式分类：行为型模式

import Foundation
typealias Memento = Dictionary<NSObject,AnyObject>

let DPMementoKeyChapter = "com.valve.halflife.chapter"
let DPMementoKeyWeapon = "com.valve.halflife.weapon"
let DPMementoGameState = "com.valve.halflife.state"

/// 游戏状态
class GameState {
    var chapter: String = ""
    var weapon: String = ""

    /** 生成游戏存档 - returns: 存档 */
    func toMemento() -> Memento {
        return [ DPMementoKeyChapter:chapter,DPMementoKeyWeapon:weapon ]
    }

    /** 恢复游戏存档 - parameter memento: 存档 */
    func restoreFromMemento(memento: Memento) {
        chapter = memento[DPMementoKeyChapter] as? String ?? "n/a"
        weapon = memento[DPMementoKeyWeapon] as? String ?? "n/a"
    }
}

/** 存档点 */
enum CheckPoint {
    /** 保存存档 - parameter memento: 存档 - parameter keyName: 存档名 */
    static func saveState(memento: Memento,keyName: String = DPMementoGameState) {
// let defaults = NSUserDefaults.standardUserDefaults()
// defaults.setObject(memento,forKey: keyName)
// defaults.synchronize()

        DB.set(keyName,obj: memento)
    }

    /** 读取存档 - parameter keyName: 存档名 - returns: 存档 */
    static func restorePrevIoUsState(keyName keyName: String = DPMementoGameState) -> Memento {
// let defaults = NSUserDefaults.standardUserDefaults()
// 
// return defaults.objectForKey(keyName) as? Memento ?? Memento()

        let m = DB.get(keyName)
        return m as? Memento ?? Memento()
    }
}

class DB {
    static var dict:Dictionary<String,AnyObject> = [:]

    class func set(key: String,obj: AnyObject) {
        dict[key] = obj
    }

    class func get(key: String) -> AnyObject? {
        return dict[key]
    }
}

func printGameStateInfo(state: GameState) -> Void {
    print("当前游戏状态：[chapter = \(state.chapter),weapon = \(state.weapon)]")
}

var gameState = GameState()
gameState.restoreFromMemento(CheckPoint.restorePrevIoUsState()) // 新游戏

printGameStateInfo(gameState)

gameState.chapter = "第一章 新手上路"
gameState.weapon = "木剑"
CheckPoint.saveState(gameState.toMemento()) // 第一个存档

printGameStateInfo(gameState)

gameState.chapter = "第二章 冒险开始"
gameState.weapon = "铜剑"
gameState.restoreFromMemento(CheckPoint.restorePrevIoUsState()) // 恢复存档

printGameStateInfo(gameState)

gameState.chapter = "第三章 挑战魔龙"
gameState.weapon = "铁剑"
CheckPoint.saveState(gameState.toMemento(),keyName: "gameState2") // 第二个存档

printGameStateInfo(gameState)

gameState.chapter = "最后章 最终之战"
gameState.weapon = "圣剑"
CheckPoint.saveState(gameState.toMemento()) // 覆盖第一个存档

printGameStateInfo(gameState)

gameState.restoreFromMemento(CheckPoint.restorePrevIoUsState(keyName: "gameState2")) // 加载第二个存档

printGameStateInfo(gameState)