public void AddItem(int id)
    {
        Item itemtoAdd = database.GetItemByID(id);


        if (itemtoAdd.Stackable && CheckifItemisInInventory(itemtoAdd))
        {
            for (int i = 0; i < inventory.Count; i++)
            {
                if (inventory[i].GetComponent <UI_Item>().item.ID == id)
                {
                    UI_Item data = inventory[i].GetComponent <UI_Item>();
                    //UI_Item data = slots[i].transform.GetChild(0).GetComponent<UI_Item>();

                    data.amount++;
                    data.transform.GetChild(0).GetComponent <Text>().text = data.amount.ToString();
                    break;
                }
            }
        }
        else
        {
            for (int i = 0; i < items.Count; i++)
            {
                if (items[i].ID == -1)
                {
                    items[i] = itemtoAdd;
                    GameObject itemObj = Instantiate(inventoryItem) as GameObject;
                    inventory.Add(itemObj);
                    itemObj.GetComponent <UI_Item>().item   = itemtoAdd;
                    itemObj.GetComponent <UI_Item>().slot   = i;
                    itemObj.GetComponent <UI_Item>().amount = 1;
                    itemObj.transform.SetParent(slots[i].transform);
                    itemObj.transform.position            = Vector2.zero;
                    itemObj.GetComponent <Image>().sprite = itemtoAdd.sprite;
                    itemObj.name = itemtoAdd.name;
                    break;
                }
            }
        }
    }