/// <summary>
/// 设置按钮层级
/// </summary>
private void FnSetBtnLayer()
{
    GameObject go = Rt_FuncBottom.gameObject;
    Canvas ca = go.GetComponent<Canvas>();
    GraphicRaycaster ray = go.GetComponent<GraphicRaycaster>();
    if (ca == null)
    {
        ca = go.AddComponent<Canvas>();
    }
    if (ray == null)
    {
        ray = go.AddComponent<GraphicRaycaster>();
    }
    ca.overrideSorting = true;
    ca.sortingOrder = canvasOrder + 1;
}