Spawner.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Spawner : MonoBehaviour
{
    public static Spawner spawner;

    public GameObject[] prefabs;
    List<GameObject>[] pools;

    void Awake ()
    {
        if (spawner == null)
        {
            spawner = this;
            DontDestroyOnLoad(gameObject);
            Setup();
        }
        else
        {
            Debug.Log("Spawner already exists, destroying this one.");
            Destroy(gameObject);
        }
    }

    void Setup ()
    {
        pools = new List<GameObject>[prefabs.Length];
        for (int i = 0; i < prefabs.Length; i++)
        {
            pools[i] = new List<GameObject>();
        }
    }

    public static GameObject GetPrefab(string objName)
    {
        for (int i = 0; i < spawner.prefabs.Length; i++)
        {
            if (objName == spawner.prefabs[i].name) return spawner.prefabs[i];
        }
        return null;
    }

    public static GameObject Spawn (string objName, Vector3 pos)
    {
        for (int i = 0; i < spawner.prefabs.Length; i++)
        {
            if (objName == spawner.prefabs[i].name)
            {
                GameObject g = spawner.pools[i].Find(CanUse);
                if (g == null)
                {
                    g = Instantiate(spawner.prefabs[i]) as GameObject;
                    spawner.pools[i].Add(g);
                }
                
                g.transform.position = pos;
                g.transform.SetParent(spawner.transform);
                g.SetActive(true);

                return g;
            }
        }
        return null;
    }

    static bool CanUse (GameObject g)
    {
        return !g.activeSelf;
    }

    public static void DisableAll()
    {
        for (int i = 0; i < spawner.prefabs.Length; i++)
        {
            for (int j = 0; j < spawner.pools[i].Count; j++)
            {
                spawner.pools[i][j].SetActive(false);
            }
        }

    }
    
}