Unity Singleton GameManager

GameManager.cs

using UnityEngine;
using System.Collections;


public class GameManager : MonoBehaviour {
  public static GameManager manager; //singleton

  void Awake(){
    if(manager == null){
      DontDestroyOnLoad(gameObject);
      manager = this;
    }else if(manager != this){
      Destroy(gameObject);
    }
  }

}