     let sprite1 = SKSpriteNode(color: UIColor(red: 1.0, green: 0.0, blue: 0.0, alpha: 1.0), size: CGSize(width: 10, height: 10))
     let sprite2 = SKSpriteNode(color: UIColor(red: 0.0, green: 1.0, blue: 0.0, alpha: 1.0), size: CGSize(width: 10, height: 10))
     let sprite3 = SKSpriteNode(color: UIColor(red: 0.0, green: 0.0, blue: 1.0, alpha: 1.0), size: CGSize(width: 10, height: 10))
+    let sprite4 = SKSpriteNode(color: UIColor(red: 1.0, green: 1.0, blue: 0.0, alpha: 1.0), size: CGSize(width: 10, height: 10))
+
+    var sprite4_selected = false
 
     override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
         /* Called when a touch begins */


            physics_body.affectedByGravity = false
            physics_body.allowsRotation = false

            s.physicsBody = physics_body
            self.addChild(s)

        for touch: AnyObject in touches {
            let location = touch.locationInNode(self)

            let action = SKAction.moveTo(location, duration: 0.01)

            // This doesn't really work that well, but it demonstrates how to move sprite4 conditionally. 
            if sprite4_selected {
                sprite4.runAction(SKAction.repeatAction(action, count: 1))
            } else {
                sprite2.runAction(SKAction.repeatAction(action, count: 1))
            }
        }
    }

