Unityでのシングルトンクラスです。

using UnityEngine;
using System.Collections;
 
//------------------------------------------------------------------------------
// シングルトン
//------------------------------------------------------------------------------
public abstract class Singleton<T> : MonoBehaviour where T : Singleton<T>
{
    //------------------------------------------------------------------
    // member
    //------------------------------------------------------------------
    private static T m_Instance = null;
 
    //------------------------------------------------------------------
    // インスタンス取得
    //------------------------------------------------------------------
	public static T Instance
	{
		get
		{
			if( m_Instance == null )
			{
				m_Instance = (T)FindObjectOfType(typeof(T) );
				if( m_Instance == null )
				{
					Debug.LogError( typeof(T) + "is nothing" );
				}
			}
			return m_Instance;
		}
	}
 
    //------------------------------------------------------------------
    // 初期化
    //------------------------------------------------------------------
    protected abstract void Initialize();
 
    //------------------------------------------------------------------
    // Awake
    //------------------------------------------------------------------
    private void Awake()
    {
        if( m_Instance != null && m_Instance != (T)this )
        {
            Destroy(gameObject);
            return;
        }
 
        Initialize();
 
        DontDestroyOnLoad( gameObject );
 
        m_Instance = (T)this;
    }
}

public class Fader : Singleton<Fader>
{
	protected override void Initialize()
	{
		// TODO
	}
}