TrafficRoad/Assets/BuildSystem/Scripts/MonoSingleton.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
namespace BuildSystem
{
    public class MonoSingleton<T> : MonoBehaviour where T : MonoSingleton<T>
    {
        private static T _instance;
        public static T Instance
        {
            get
            {
                return _instance;
            }
        }

        protected virtual void Awake()
        {
            if (_instance != null)
            {
                Destroy(_instance.gameObject);
            }
            _instance = this as T;
        }

        protected virtual void OnDestroy()
        {
            if (_instance == this)
            {
                _instance = null;
            }
        }
    }
}