Weird Compiler Error

GameScene.swift

//
//  GameScene.swift
//  EmitterDemo
//
//


// colorize function takes HEX and Alpha converts then returns aUIColor object
func colorize (hex: Int, alpha: Double = 1.0) -> UIColor {
    let red = Double((hex & 0xFF0000) >> 16) / 255.0
    let green = Double((hex & 0xFF00) >> 8) / 255.0
    let blue = Double((hex & 0xFF)) / 255.0
    var color: UIColor = UIColor( red: Float(red), green: Float(green), blue: Float(blue), alpha:Float(alpha) )
    return color
}

import SpriteKit

class GameScene: SKScene {
    override func didMoveToView(view: SKView) {
        
        // blue background color
        self.backgroundColor = colorize( 0x003342, alpha:1.0)
    
    }
    
    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        /* Called when a touch begins */
        
        for touch: AnyObject in touches {
            let location = touch.locationInNode(self)
            
            let sprite = SKSpriteNode(imageNamed:"Spaceship")
            
            sprite.xScale = 0.5
            sprite.yScale = 0.5
            sprite.position = location
            
            let action = SKAction.rotateByAngle(CGFloat(M_PI), duration:1)
            
            sprite.runAction(SKAction.repeatActionForever(action))
            
            self.addChild(sprite)
        }
    }
   
    override func update(currentTime: CFTimeInterval) {
        /* Called before each frame is rendered */
    }
}

GameViewController.swift

//
//  GameViewController.swift
//  EmitterDemo
//
//

import UIKit
import SpriteKit

extension SKNode {
    class func unarchiveFromFile(file : NSString) -> SKNode? {
        
        let path = NSBundle.mainBundle().pathForResource(file, ofType: "sks")
        
        var sceneData = NSData.dataWithContentsOfFile(path, options: .DataReadingMappedIfSafe, error: nil)
        var archiver = NSKeyedUnarchiver(forReadingWithData: sceneData)
        
        archiver.setClass(self.classForKeyedUnarchiver(), forClassName: "SKScene")
        let scene = archiver.decodeObjectForKey(NSKeyedArchiveRootObjectKey) as GameScene
        archiver.finishDecoding()
        return scene
    }
}

class GameViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        if let scene = GameScene.unarchiveFromFile("GameScene") as? GameScene {
            // Configure the view.
            let skView = self.view as SKView
            skView.showsFPS = true
            skView.showsNodeCount = true
            
            /* Sprite Kit applies additional optimizations to improve rendering performance */
            skView.ignoresSiblingOrder = true
            
            /* Set the scale mode to scale to fit the window */
            scene.scaleMode = .AspectFill
            
            skView.presentScene(scene)
        }
    }

    override func shouldAutorotate() -> Bool {
        return true
    }

    override func supportedInterfaceOrientations() -> Int {
        if UIDevice.currentDevice().userInterfaceIdiom == .Phone {
            return Int(UIInterfaceOrientationMask.AllButUpsideDown.toRaw())
        } else {
            return Int(UIInterfaceOrientationMask.All.toRaw())
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Release any cached data, images, etc that aren't in use.
    }
    
}