let bullet = SKSpriteNode(fileNamed: "Bullet")
      bullet?.size = CGSize(width: 100, height: 100)
      bullet.zPosition = -5

      bullet.position = CGPointMake(player.position.x, player.position.y)
      bullet.zRotation = player.zRotation


      let action = SKAction.moveToY(self.size.height + 30, duration: 0.8)
      let actionDone = SKAction.removeFromParent()
      bullet.runAction(SKAction.sequence([action, actionDone]))

      bullet.physicsBody = SKPhysicsBody(rectangleOfSize: bullet.size)
      bullet.physicsBody?.affectedByGravity = false
      bullet.physicsBody?.dynamic = false
      self.addChild(bullet)