Current save game data

save.swift

import SpriteKit


class GameData : NSObject, NSCoding {
    
    /// Each scene always knows what scene should come next.
    /// So, by storing the current scene, we can just resume that scene when the game is reloaded
    /// If the user quits on a level, use logic to show world map instead
    /// NOTE** -- save SceneObject instead? so that userData is remembered, and it just pass this to scene manager?
    var currentScene : String = "MainMenu"
    
    /// Reference to LevelData array which contains both static and saved data
    var levelData : LevelData?
    
    /// Reference to the current army
    var army : ArmyData?
    
    /// Create of shared instance
    
    class var sharedInstance: GameData {
        
        struct Static {
            static var instance: GameData?
            static var token: dispatch_once_t = 0
        }
        
        dispatch_once(&Static.token) {
            var gamedata = GameData()
            if let savedData = GameData.loadGame() {
                gamedata.levelData = savedData.levelData
                gamedata.army = savedData.army
                
                // hard code different setups for testing
                // this will override the saved file
                //gamedata.levelData?.setTestingData()
            }
            Static.instance = gamedata
        }
        
        return Static.instance!
    }
    
    override init() { 
        super.init()
        self.levelData = LevelData()
        self.army = ArmyData()
    }
    
    required init(coder: NSCoder) {
        super.init()
        self.currentScene = coder.decodeObjectForKey("currentScene") as! String
        self.levelData = coder.decodeObjectForKey("levelData") as? LevelData
        self.army = coder.decodeObjectForKey("army") as? ArmyData
    }
    
    func encodeWithCoder(coder: NSCoder) {
        coder.encodeObject(GameData.sharedInstance.currentScene, forKey: "currentScene")
        coder.encodeObject(GameData.sharedInstance.levelData, forKey: "levelData")
        coder.encodeObject(GameData.sharedInstance.army, forKey: "army")
    }
    
    /// Loading and saving
    
    class func loadGame() -> GameData? {
        // load existing high scores or set up an empty array
        let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)
        let documentsDirectory = paths[0] as! String
        let path = documentsDirectory.stringByAppendingPathComponent("GameData.plist")
        let fileManager = NSFileManager.defaultManager()
        
        // check if file exists
        if !fileManager.fileExistsAtPath(path) {
            // create an empty file if it doesn't exist
            if let bundle = NSBundle.mainBundle().pathForResource("DefaultFile", ofType: "plist") {
                fileManager.copyItemAtPath(bundle, toPath: path, error:nil)
            }
        }
        
        if let rawData = NSData(contentsOfFile: path) {
            // do we get serialized data back from the attempted path?
            // if so, unarchive it into an AnyObject, and then convert to an array of HighScores, if possible
            if let data = NSKeyedUnarchiver.unarchiveObjectWithData(rawData) as? GameData {
                return data
            }
        }
        
        return nil
    }
    
    func save() {
        
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), {
            // find the save directory our app has permission to use, and save the serialized version of self.scores - the HighScores array.
            let saveData = NSKeyedArchiver.archivedDataWithRootObject(GameData.sharedInstance)
            let paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true) as NSArray
            let documentsDirectory = paths.objectAtIndex(0) as! NSString
            let path = documentsDirectory.stringByAppendingPathComponent("GameData.plist")
            
            saveData.writeToFile(path, atomically: true)
        })
    }
    
}

What should we include in that plist file?