ChivaFrameWork/Framework/Toolkits/Singleton/Singleton.cs

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

public class Singleton<T> where T : class , new()
{
    private static readonly object _lock = new object();

    private static T _instance;

    public static T Instance
    {
        get
        {
            lock (_lock)
            {
                if (_instance == null)
                {
                    _instance = new T();
                }
            }

            return _instance;
        }
    }
}