MonoSingletonFromResources.cs

MonoSingletonFromResources.cs

using System;
using UnityEngine;

public abstract class MonoSingletonFromResources<T> : MonoBehaviour where T : MonoSingletonFromResources<T>
{
    private static readonly string RESOURCES_PATH = "Prefabs/Singletons/";
    static T m_Instance = null;

    public static T instance
    {
        get
        {
            if( m_Instance != null )
            {
                return m_Instance;
            }

            System.Type type = typeof(T);

            T instance = GameObject.FindObjectOfType(type) as T;

            if( instance == null )
            {
                string typeName = type.ToString();

                try{
                    GameObject gameObject = Instantiate (Resources.Load (RESOURCES_PATH + type.Name)) as GameObject;
                    instance = gameObject.GetComponent<T>();
                    gameObject.name = type.Name;
                }catch(ArgumentException e){
                    Debug.LogError ("Problem during the creation of " + typeName);
                }
            }
            else
            {
                Initialize(instance);
            }
            return m_Instance;
        }
    }

    static void Initialize(T instance)
    {
        if( m_Instance == null )
        {
            m_Instance = instance;

            m_Instance.OnInitialize();
        }
        else if( m_Instance != instance )
        {
            DestroyImmediate( instance.gameObject );
        }
    }

    static void Destroyed(T instance)
    {
        if( m_Instance == instance )
        {
            m_Instance.OnFinalize();
        }
    }

    public virtual void OnInitialize() {}
    public virtual void OnFinalize() {
        //FindObjectOfTypeは負荷が多いため繰り返す場合ば解放しない
        m_Instance = null;
    }

    void Awake()
    {
        Initialize( this as T );
    }

    void OnDestroy()
    {
        Destroyed( this as T );
    }

    void OnApplicationQuit()
    {
        Destroyed( this as T );
    }
}