EventHandlerUI.cs

    private bool gunButtonDown;
    public float fireRate;
    private float fireTime;
    
    void Update()
    {
        // Only fire if button is down 
        if (gunButtonDown && Time.time > nextFire)
        {
            GunFire();
            nextFire = Time.time + fireRate;
        }
    }
    
    public void GunButtonDown()
    {
        gunButtonDown = true;
    }

    public void GunButtonUp()
    {
        gunButtonDown = false;
    }