Unity3D에서의 싱글톤 구현

//컴포넌트 기반 싱글톤
//-------------------------------------------------------------------------------------------

using UnityEngine;

public class MySingleton : MonoBehaviour
{
    private static MySingleton instance;
	
    public static MySingleton Instance
    {
        get
        {
            if ( instance == null )
               instance = new GameObject("MySingleton").AddComponent( );

            return instance;
        }
    }

    public void OnApplicationQuit( ) 
    {
        instance = null;
    }
}


//-------------------------------------------------------------------------------------------
//사용 예)

public class MySingleton
{
    private static MySingleton instance; // 인스턴스 

    public MySingleton( )
    {
        if ( instance != null )
        {
            Debug.LogError( "Can't have two instances of singleton !!" );
            return;
        }
        instance = this;
    } 

    public static MySingleton Instance
    {
        get
        {
            if ( instance == null )
               new MySingleton( ); //첫 인스턴스 생성 

            return instance;
        }
    } 

    private int score;    // 내부 데이터 변수

    public int Score
    {
        get {
            return scroe;
        } set {
            score = value;
        }
    }
}

//-------------------------------------------------------------------------------------------
MySingleton.Instance.Score += 9;
Debug.Log( "Score is now: " + MySingleton.Instance.Score );
 

//템플릿 기반 싱글톤
//-------------------------------------------------------------------------------------------

using UnityEngine;

public abstract class MonoSingleton< T > : MonoBehaviour where T : MonoSingleton< T >
{
    private static T m_Instance = null;

    public static T instance
    {
        get
        {
            if ( m_Instance == null )
            {
                m_Instance = GameObject.FindObjectOfType( typeof(T) ) as T; 

                if ( m_Instance == null)
                   Debug.LogError( "No instance of " + typeof(T).ToString( ) ); 

                m_Instance.Init( );
             }
            return m_Instance;
        }
    } 

    private void Awake( )
    {
        if ( m_Instance == null )
        {
            m_Instance = this as T;
            m_Instance.Init( );
        }
    } 

    public virtual void Init( ) { } // 초기화를 상속을 통해 구현    

    private void OnApplicationQuit( )
    {
        m_Instance = null;
    }
}

//-------------------------------------------------------------------------------------------
//사용 예)

GameManager.cs 

public class GameManager : MonoSingleton< GameManager >
{
    public int difficulty = 0;
    public override void Init( ) { difficulty = 5; }
}

//-------------------------------------------------------------------------------------------
OtherClass.cs 

using UnityEngine;
public class OtherClass : MonoBehaviour
{
    void Start( ) 
    { 
        print( GameManager.instance.difficulty ); 
    }
}

출처 : http://blog.naver.com/rapha0/110154460575