BasicFantasy/Assets/Scripts/UnitySingleton.cs

using UnityEngine;

namespace FirstVillain.Singleton
{
    public class UnitySingleton<T> : MonoBehaviour where T : UnityEngine.Component
    {
        private static T _instance = null;

        public static T Instance
        {
            get
            {
                if (_instance == null)
                {
                    string name = (typeof(T)).ToString();
                    _instance = new GameObject(name).AddComponent<T>();
                }

                return _instance;
            }
        }
        private void Awake()
        {
            if (_instance != null && _instance != this)
            {
                Destroy(gameObject);
                return;
            }
            else
            {
                _instance = this as T;
            }

            DontDestroyOnLoad(gameObject);

            AwakeSingleton();
        }

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

        protected virtual void AwakeSingleton()
        { }
    }
    public class UnitySingletonOnce<T> : MonoBehaviour where T : UnityEngine.Component
    {
        private static T _instance = null;

        public static T Instance
        {
            get
            {
                if (_instance == null)
                {
                    string name = (typeof(T)).ToString();
                    _instance = new GameObject(name).AddComponent<T>();
                }

                return _instance;
            }
        }
        private void Awake()
        {
            if (_instance != null && _instance != this)
            {
                Destroy(gameObject);
                return;
            }
            else
            {
                _instance = this as T;
            }

            AwakeSingleton();
        }

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

        protected virtual void AwakeSingleton()
        { }
    }
}