void TouchMove()
    {
        if (Input.touchCount > 0)
        {
            Touch touch = Input.GetTouch(0);
            float middle = Screen.width / 2;

            if (touch.position.x < middle && touch.phase == TouchPhase.Began)
            {
                MoveLeft();
            }

            else if (touch.position.x > middle && touch.phase == TouchPhase.Began)
            {
                MoveRight();
            }
        }
        else
        {
            SetVelocityZero();
        }
    }

    public void MoveLeft()
    {
        rb.velocity = new Vector2(-playerSpeed, 0);
    }

    public void MoveRight()
    {
        rb.velocity = new Vector2(playerSpeed, 0);
    }

    public void SetVelocityZero()
    {
        rb.velocity = Vector2.zero;
    }
}