Mono singleton Class. Extend this class to make singleton component.

MonoSingleton.cs

using UnityEngine;
using System.Collections;
using System.Collections.Generic;

/// <summary>
/// Mono singleton Class. Extend this class to make singleton component.
/// Example: 
/// <code>
/// public class Foo : MonoSingleton<Foo>
/// </code>. To get the instance of Foo class, use <code>Foo.instance</code>
/// Override <code>Init()</code> method instead of using <code>Awake()</code>
/// from this class.
/// </summary>
public abstract class MonoSingleton<T> : MonoBehaviour where T : MonoSingleton<T>
{
    private static T m_Instance = null;
    public static T instance
    {
        get
        {
            // Instance requiered for the first time, we look for it
            if( m_Instance == null )
            {
                m_Instance = GameObject.FindObjectOfType(typeof(T)) as T;

                // Object not found, we create a temporary one
                if( m_Instance == null )
                {
  				Debug.LogWarning("No instance of " + typeof(T).ToString() + ", a temporary one is created.");

					isTemporaryInstance = true;
                    m_Instance = new GameObject("Temp Instance of " + typeof(T).ToString(), typeof(T)).GetComponent<T>();

                    // Problem during the creation, this should not happen
                    if( m_Instance == null )
                    {
                        Debug.LogError("Problem during the creation of " + typeof(T).ToString());
                    }
                }
				if (!_isInitialized){
					_isInitialized = true;
					m_Instance.Init();
				}
            }
            return m_Instance;
        }
    }

	public static bool isTemporaryInstance { private set; get; }

	private static bool _isInitialized;

    // If no other monobehaviour request the instance in an awake function
    // executing before this one, no need to search the object.
    private void Awake()
    {
        if (m_Instance == null) {
			m_Instance = this as T;
		} else if (m_Instance != this) {
			Debug.LogError ("Another instance of " + GetType () + " is already exist! Destroying self...");
			DestroyImmediate (this);
			return;
		}
		if (!_isInitialized) {
			DontDestroyOnLoad(gameObject);
			_isInitialized = true;
			m_Instance.Init ();
		}
    }
	
	
    /// <summary>
    /// This function is called when the instance is used the first time
    /// Put all the initializations you need here, as you would do in Awake
    /// </summary>
	public virtual void Init(){}
 
    /// Make sure the instance isn't referenced anymore when the user quit, just in case.
    private void OnApplicationQuit()
    {
        m_Instance = null;
    }
}