NSUserDefault GlobalData/Base Scene Multiple "Keys" Overall Total

Question

I have multiple scenes that are stored in Global/BaseScene

Each SceneType: is stored as enum: set to an Integer similar to this present scene

First objective was to get the score to populate in each scene, there is seven of them. DONE thanks to stack overflow, and experimentation

I had to create default keys for each individual scene, to calculate the highScore, so I have seven unique "highScore" "keys" for each scene.

In the GameScene:

var highScoreA1: Int = 0  
    var score: Int = 0 {
         didSet { 
             a1Score.text = "Score: \(score)"
         }
      }

//above called before override func didMoveToView(view: SKView) { 

//Called in GameOver Method 
let scoreDefault = NSUserDefaults.standardUserDefaults()
scoreDefault.setInteger(score, forKey: "score")

if (score > highScoreA1){

let highScoreA1Default = NSUserDefaults.standardUserDefaults() 

highScoreA1Default.setInteger(score, forKey: "highScoreA1")
//highscoreA1Default.synchronize()         

There are six more keys similar to this.. My objective is to populate a "totalScoreKey" in two different scenes a Hud Scene and another scene (possibly game over scene)

I was thinking a function to add these keys together to populate the total score. Taking into consideration all these scenes are subclasses (of Global BaseScene, and each scene has sub classes (for the nodes operation, probably not relevant yet thought it might be useful)

I have tried: Moving all score data into a Class and using NSCoding/NSObject the required init, and optional binding, became a serious pain, and honestly I am trying to keep things simple for version one.

import Foundation

    class GameState {
        var score:Int = 0
        var highScore:Int()
        var totalScore:Int()

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

            return Singleton.instance
        }
    }
    init() {
        // Init
        score.type = 0
        highScore = 0
        totalScore = 0

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

        highScore = defaults.integerForKey("highScore")

    }

    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(totalScore, forKey: "totalScore")
        NSUserDefaults.standardUserDefaults().synchronize()
    }

Various functions that have not worked they all default to zero, that is until I figure out how to retrieve data properly.

let total score = "totalScoreKey"

similar to this post exactly like this post actually except I had to do different configurations because of my on personal set up..

total Score example I tried to implement

outside of class and referring to that in the scene I needed to populate that data. NO Go defaults to zero.

How do I simply add the value of those keys together? For which I can display similar to the other scenes, I already have implemented. later on down the road I may want to assign a key chain value, right now I am just trying to get it show up for posting in GameCenter. (which also has key "GameCenterHighScore")

Setting them all to the same key "highScore" does not work.... just to be clear, I tried multiple times. Thanks in advance.

EDIT if I try to add all the defaults together to get the total, it throws the following error:

Expression was too complex to be solved in reasonable time; consider breaking up the expression into distinct sub-expressions [Swift compound arithmetic operation ERROR3