TapCommon-Unity/Runtime/Internal/UI/Base/MonoSingleton.cs

using System;
using UnityEngine;

namespace TapTap.UI
{
    public class MonoSingleton<T> : MonoBehaviour where T : Component
    {
        private static T _instance;

        public static T Instance
        {
            get
            {
                if (_instance == null && Application.isPlaying)
                {
                    CreateInstance();
                }

                return _instance;
            }
        }

        private static void CreateInstance()
        {
            Type theType = typeof(T);

            _instance = (T)FindObjectOfType(theType);

            if (_instance == null)
            {
                var go = new GameObject(typeof(T).Name);
                _instance = go.AddComponent<T>();

                GameObject rootObj = GameObject.Find("TapSDKSingletons");
                if (rootObj == null)
                {
                    rootObj = new GameObject("TapSDKSingletons");
                    DontDestroyOnLoad(rootObj);
                }

                go.transform.SetParent(rootObj.transform);
            }
        }

        public static void DestroyInstance()
        {
            if (_instance != null)
            {
                Destroy(_instance.gameObject);
            }
        }

        public static bool HasInstance()
        {
            return _instance != null;
        }

        protected virtual void Awake()
        {
            if (_instance != null && _instance.gameObject != gameObject)
            {
                if (Application.isPlaying)
                {
                    Destroy(gameObject);
                }
                else
                {
                    DestroyImmediate(gameObject); // UNITY_EDITOR
                }

                return;
            }
            else if (_instance == null)
            {
                _instance = GetComponent<T>();
            }

            DontDestroyOnLoad(gameObject);

            Init();
        }

        protected virtual void OnDestroy()
        {
            Uninit();

            if (_instance != null && _instance.gameObject == gameObject)
            {
                _instance = null;
            }
        }

        protected virtual void Init()
        {
        }

        public virtual void Uninit()
        {
        }

    }
}