private void GridUI_OnLeftEndDrag(Transform preTransform, Transform nowTransform)
    {
        isDrag = false;
        dragItem.Hide();

        if (nowTransform == null)                 //拖到背包外面,扔掉
        {
            ItemModel.DelItem(preTransform.name); //删掉背包数据库中原来格子里的数据
        }
        else if (nowTransform.tag == "Grid")      //拖到了另一个格子
        {
            if (nowTransform.childCount == 0)     //是空格子,放入
            {
                Item preItem = ItemModel.GetItem(preTransform.name);
                CreateItem(preItem, nowTransform);
                ItemModel.DelItem(preTransform.name);
            }
            else                               //不是空格子,交换
            {
                Destroy(nowTransform.GetChild(0).gameObject);
                Item preItem = ItemModel.GetItem(preTransform.name);
                Item nowItem = ItemModel.GetItem(nowTransform.name);

                CreateItem(preItem, nowTransform);
                CreateItem(nowItem, preTransform);
            }
        }
        else                                //不在背包的格子里面,放回去
        {
            Item item = ItemModel.GetItem(preTransform.name);
            CreateItem(item, preTransform);
        }
    }