[游戏开发]Unity Singleton

using UnityEngine;

public abstract class Singleton<T> : MonoBehaviour where T : Component
{
    private static T instance;

    private static bool m_applicationIsQuitting = false;

    public static T GetInstance()
    {
        if (m_applicationIsQuitting) { return null; }

        if (instance == null)
        {
            instance = FindObjectOfType<T>();
            if (instance == null)
            {
                GameObject obj = new GameObject();
                obj.name = typeof(T).Name;
                instance = obj.AddComponent<T>();
            }
        }
        return instance;
    }

    protected virtual void Awake()
    {
        if (instance == null)
        {
            instance = this as T;
            DontDestroyOnLoad(gameObject);
        }
        else if (instance != this as T)
        {
            Destroy(gameObject);
        }
        else { DontDestroyOnLoad(gameObject); }
    }

    private void OnApplicationQuit()
    {
        m_applicationIsQuitting = true;
    }
}

IMPROPER USAGE

1. Don’t call GetInstance from another objects Awake function
2. Don’t use 1 singleton to access every important variable in your game
3. Don’t use singletons just to access data or references if they are not part of the design

MAIN AREAS THEY WON’T WORK

1. Unit Tests because they require copies/mock objects to test
2. Multithreading