//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 ); 
    }
}

2. In Unity Editor go to Edit->Preferences->External Tools and In External Script Editor choose Browse from the drop down box.
3. Browse to and select C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\devenv.exe.
4. The External Script Editor should automatically show your selected editor as Visual Studio 2013.
5. That’s it! It should just work from that point on.
6. 
   
7. Edit->Preferences->External Tools
8. 
   
9. 
   
10. 플러그인 설치 http://unityvs.com/
11. "UnityVS_1.8.1-2013"
13.  - Copy SyntaxTree.VisualStudio.Packages.dll to:
14.  C:\Program Files (x86)\Microsoft Visual Studio 12.0\Common7\IDE\Extensions\SyntaxTree\UnityVS