void AddNewGridItem(Item item, bool stackable)
    {
        GridItem gItem;

        if (!stackable)
        {
            gItem = ObjectPoolManager.Instance.GetObject <GridItem>(GRID_PREFAB_KEY);
        }
        else
        {
            gItem = ObjectPoolManager.Instance.GetObject <StackableGridItem>(STACKABLE_GRID_PREFAB_KEY);
        }

        InventoryUI.AddNewGridItem(gItem, item);

        if (_items.ContainsKey(item.Id))
        {
            List <GridItem> gridItems = new List <GridItem>();

            gridItems = _items[item.Id];

            gridItems.Add(gItem);
        }
        else
        {
            _items.Add(item.Id, new List <GridItem>()
            {
                gItem
            });
        }
    }