Why does the item only appear on colliders?

Question

C++ / C#

There is a script, and when I want to spawn an item using this script, it only appears where there is a collider (any), is it possible to make items appear only in a specific collider (trigger)?

// NULLcode Studio © 2015
// null-code.ru

using UnityEngine;
using UnityEngine.UI;
using System;
using System.Collections;

public class Inventory : MonoBehaviour {

  public Transform[] allItems;
  public Sprite[] itemIcon;
  public int iconSize = 50;
  public Sprite background;
  private GameObject[] cell;
  private Texture2D tmpTexture;
  private int iconCoumt;
  private int itemCoumt;
  private GameObject tmpObject;
  private GameObject cell_tmp;
  private Vector2 curPos;
  public static int grid_id;

  void Awake ()
  {
    grid_id = -1;
    cell = new GameObject[transform.childCount];
    for(int j = 0; j < cell.Length; j++)
    {
      cell[j] = transform.GetChild(j).gameObject;
      cell[j].GetComponentInChildren<Grid>().ID = j;
    }
  }

  void Reset()
  {
    if(tmpTexture)
    {
      tmpTexture = null;
      if(grid_id == -1 && !tmpObject)
      {
        // создание объекта с добавлением высоты по Y
        GameObject clone = Instantiate(allItems[itemCoumt].gameObject, curPos, Quaternion.identity);
      }
    }
    if(tmpObject)
    {
      tmpObject.SetActive(true);
      tmpObject = null;
    }
    cell_tmp = null;
  }

  void Update () 
  {
    RaycastHit2D hit = Physics2D.Raycast(Camera.main.ScreenToWorldPoint(Input.mousePosition), Vector3.zero);
    if (hit.collider != null)
    {
      curPos = hit.point;
      if(Input.GetMouseButton(0))
      {
        if(hit.transform.GetComponent<AddToInventory>() && !tmpTexture)
        {
          tmpObject = hit.transform.gameObject;
          tmpObject.SetActive(false);
          int i = hit.transform.GetComponent<AddToInventory>().itemID;
          for(int j = 0; j < itemIcon.Length; j++)
          {
            // поиск id массива иконок, относительно номера объекта
            string n = itemIcon[j].name.Split(new char[] {'_'}, StringSplitOptions.RemoveEmptyEntries)[0];
            if(n == i.ToString())
            {
              tmpTexture = itemIcon[j].texture;
              iconCoumt = j;
              for(int f = 0; f < allItems.Length; f++)
              {
                // поиск id массива предметов, относительно номера объекта
                n = allItems[f].name.Split(new char[] {'_'}, StringSplitOptions.RemoveEmptyEntries)[0];
                if(n == i.ToString()) itemCoumt = f;
              }
            }
          }
        }
      }
      else
      {
        if(!Input.GetMouseButton(0) && grid_id == -1) Reset();
      }
    }
    else
    {
      if(!Input.GetMouseButton(0) && grid_id == -1) Reset();
    }

    if(Input.GetMouseButtonUp(0) && grid_id > -1 && tmpTexture)
    {
      foreach(GameObject obj in cell)
      {
        GameObject tmp = obj.transform.GetChild(0).gameObject;

        // меняем местами иконки, внутри рюкзака
        if(tmp.GetComponent<Grid>().ID == grid_id && tmp.GetComponent<Grid>().active && cell_tmp) 
        {
          cell_tmp.GetComponent<Grid>().icon_id = tmp.GetComponent<Grid>().icon_id;
          cell_tmp.GetComponent<Grid>().item_id = tmp.GetComponent<Grid>().item_id;
          cell_tmp.GetComponent<Grid>().active = true;
          cell_tmp.GetComponent<Image>().sprite = itemIcon[tmp.GetComponent<Grid>().icon_id];

          tmp.GetComponent<Grid>().item_id = itemCoumt;
          tmp.GetComponent<Grid>().icon_id = iconCoumt;
          tmp.GetComponent<Grid>().active = true;
          tmp.GetComponent<Image>().sprite = itemIcon[iconCoumt];

          Reset();
        }

        // добавление новой иконки в инвентарь
        if(tmp.GetComponent<Grid>().ID == grid_id && !tmp.GetComponent<Grid>().active) 
        {
          tmp.GetComponent<Grid>().item_id = itemCoumt;
          tmp.GetComponent<Grid>().icon_id = iconCoumt;
          tmp.GetComponent<Grid>().active = true;
          tmp.GetComponent<Image>().sprite = itemIcon[iconCoumt];
          Destroy(tmpObject);
        }
      }
      Reset();
    }

    if(Input.GetMouseButtonDown(0) && grid_id > -1 && !tmpTexture)
    {
      foreach(GameObject obj in cell)
      {
        GameObject tmp = obj.transform.GetChild(0).gameObject;

        // выбор иконки из рюкзака
        if(tmp.GetComponent<Grid>().ID == grid_id && tmp.GetComponent<Grid>().active) 
        {
          cell_tmp = tmp;
          iconCoumt = tmp.GetComponent<Grid>().icon_id;
          itemCoumt = tmp.GetComponent<Grid>().item_id;
          tmp.GetComponent<Grid>().active = false;
          tmpTexture = tmp.GetComponent<Image>().sprite.texture;
          tmp.GetComponent<Image>().sprite = background;
        }
      }
    }
  }

  void OnGUI () 
  {
    if(tmpTexture)
    {
      // перемещение иконки на экране
      Vector2 mousePos = Event.current.mousePosition;
      GUI.depth = 999; // поверх остальных элементов
      float shift = iconSize / 2;
      GUI.Label(new Rect(mousePos.x - shift, mousePos.y - shift, iconSize, iconSize), tmpTexture);
    }
  }
}

Answer 1

You can make it appear in the collider, but you somehow need to select the required collider, for example:
void OnTriggerStay(Collider _col)
{
if (_col.tag == "point")
{
GameObject clone = Instantiate(allItems[itemCoumt].gameObject , _col.gameObject.transform.position, Quaternion.identity);
}
}

Answer 2

If I understand correctly, by pressing a button in the inventory you want to spawn something at one specific point? Inside the Reset method, you call Instantiate with the curPos parameter, just change curPos to something else and that's it.
PS Calling a method Reset is a bad idea, it's a reserved unity keyword, along with Update and Awake.