             dt = 0
         }
         lastUpdateTime = currentTime
-        print("\(dt*1000) milliseconds since last update")
+        boundsCheckZombie()
+        rotateSprite(zombie, direction: velocity)
     }
     
     func moveSprite(sprite: SKSpriteNode, velocity: CGPoint) {
         // 1
         let amountToMove = CGPoint(x: velocity.x * CGFloat(dt), y: velocity.y * CGFloat(dt))
-        print("Amount to move: \(amountToMove)")
         
         // 2
         sprite.position = CGPoint(x: sprite.position.x + amountToMove.x, y: sprite.position.y + amountToMove.y)

    
    func moveZombieToward(location: CGPoint) {
        let offset = CGPoint(x: location.x - zombie.position.x, y: location.y - zombie.position.y)
    }
}

    var dt: NSTimeInterval = 0
    let zombieMovePointsPerSec: CGFloat = 480.0
    var velocity = CGPoint.zero
    let playableRect: CGRect
    
    override init(size: CGSize) {
        let maxAspectRatio:CGFloat = 16.0/9.0 // 1
        let playableHeight = size.width / maxAspectRatio // 2
        let playableMargin = (size.height-playableHeight)/2.0 // 3
        playableRect = CGRect(x: 0, y: playableMargin,
                              width: size.width,
                              height: playableHeight) // 4
        super.init(size: size) // 5
    }
    
    required init(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented") // 6
    }
    
    override func didMoveToView(view: SKView) {
        backgroundColor = SKColor.blackColor()
