HoHCI-BikeSteering/Assets/Scripts/Pools/Pool.cs

using System.Collections.Generic;
using UnityEngine;

namespace Pools
{
    public class Pool : MonoBehaviour
    {
        public int initialSize = 10;
        public int amountIncrease = 5;
        public GameObject prefab;
        private HashSet<GameObject> active;

        private Queue<GameObject> inactive;

        private void Awake()
        {
            active = new HashSet<GameObject>();
            inactive = new Queue<GameObject>();
            IncreasePool(initialSize);
        }

        private void IncreasePool(int amount)
        {
            for (var i = 0; i < amount; i++)
            {
                var item = Instantiate(prefab, transform);
                item.SetActive(false);
                inactive.Enqueue(item);
            }
        }


        public GameObject GetItem()
        {
            GameObject item;
            if (inactive.Count > 0)
            {
                item = inactive.Dequeue();
            }
            else
            {
                IncreasePool(amountIncrease);
                item = inactive.Dequeue();
            }

            item.transform.SetPositionAndRotation(Vector3.zero, Quaternion.Euler(Vector3.zero));
            item.SetActive(true);
            active.Add(item);
            return item;
        }

        public void ReturnToPool(GameObject item)
        {
            if (active.Remove(item))
            {
                item.SetActive(false);
                inactive.Enqueue(item);
            }
        }
    }
}