问从另一个类访问int

EN

class GameOver: SKScene {

let score = GameScene().score

init(size: CGSize, won:Bool) {

    super.init(size: size)

    backgroundColor = SKColor.whiteColor()

    var message = "\(score)"

    println(score)

    let label = SKLabelNode(fontNamed: "AvenirNextCondensed-Heavy")
    label.text = message
    label.fontSize = 40
    label.fontColor = SKColor.blackColor()
    label.position = CGPoint(x: size.width/2, y: size.height/2)
    addChild(label)
}

class GameScene: SKScene, SKPhysicsContactDelegate {

struct PhysicsCategory {
    static let None: UInt32 = 0
    static let All: UInt32 = UInt32.max
    static let Enemy: UInt32 = 0b1
    static let Player: UInt32 = 0b10
}

let player = SKSpriteNode(imageNamed: "Player")
var playerAlive: Bool = true

var touched:Bool = false
var location = CGPointMake(0, 0)

var difficulty = 1.0

var timer: NSTimer!
var scoreTimer: NSTimer!
var lastAddedTime : CFTimeInterval = 0

var score: Int = 0
var scoreLabel: SKLabelNode!


override func didMoveToView(view: SKView) {
    backgroundColor = SKColor.whiteColor()

    player.position = CGPoint(x: size.width * 0.5, y: size.height * 0.25)
    player.physicsBody = SKPhysicsBody(circleOfRadius: player.size.width/2)
    player.physicsBody?.dynamic = true
    player.physicsBody?.categoryBitMask = PhysicsCategory.Player
    player.physicsBody?.contactTestBitMask = PhysicsCategory.Enemy
    player.physicsBody?.collisionBitMask = PhysicsCategory.None
    player.physicsBody?.usesPreciseCollisionDetection = true
    addChild(player)

    physicsWorld.gravity = CGVectorMake(0, 0)
    physicsWorld.contactDelegate = self

    var timer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: "increaseDifficulty", userInfo: nil, repeats: true)

    var scoreTimer = NSTimer.scheduledTimerWithTimeInterval(1.0, target: self, selector: "addScore", userInfo: nil, repeats: true)

    scoreLabel = SKLabelNode(fontNamed: "AvenirNextCondensed-Heavy")
    scoreLabel.text = "\(score)"
    scoreLabel.fontColor = SKColor.blackColor()
    scoreLabel.fontSize = 40
    scoreLabel.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame) + self.frame.size.height * 0.4)
    addChild(scoreLabel)

}

func addScore() {
    score += 1
    println(score)
}