Game manager Object reference not set to an instance of an object

Questions & Answers
1

I was following along with a video about a [scene manager][1] and some other tips.

I am getting an error when I run it. “Object reference not set to an instance of an object” for the line with

updateDelegates[(int)State.Reset] = UpdateSceneReset;

I am still fairly new to c# so I am having trouble finding out what reference is not set to an instance.

using UnityEngine;
using System.Collections;

public class Manager : MonoBehaviour 
{
	public static Manager manager;
	private string currentScene;
	private string nextScene;
	private AsyncOperation resourceUnload;
	private AsyncOperation sceneLoad;
	private enum State { Reset, Preload, Load, Unload, Post, Ready, Run, Count };
	private State state;
	private delegate void UpdateDelegate();
	private UpdateDelegate[] updateDelegates;

	// Use this for initialization
	public void Awake () 
	{
		Object.DontDestroyOnLoad(gameObject);

		manager = this;
            // the error is for the line below
		updateDelegates[(int)State.Reset] = UpdateSceneReset;
		updateDelegates[(int)State.Preload] = UpdateScenePreload;
		updateDelegates[(int)State.Load] = UpdateSceneLoad;
		updateDelegates[(int)State.Unload] = UpdateSceneUnload;
		updateDelegates[(int)State.Post] = UpdateScenePost;
		updateDelegates[(int)State.Ready] = UpdateSceneReady;
		updateDelegates[(int)State.Run] = UpdateSceneRun;

		nextScene = "Main Menu";
		state = State.Reset;
	}

	public static void SwitchScene(string scene)
	{
		if(manager != null)
		{
			if(manager.currentScene != scene)
			{
				manager.nextScene = scene;
			}
		}
	}
	
	protected void Update()
	{
		if(updateDelegates[(int)state] != null)
		{
			updateDelegates[(int)state]();
		}
	}

	// GC old scene
	private void UpdateSceneReset()
	{
		System.GC.Collect();
		state = State.Preload;
	}

	// Start loading the new scene
	private void UpdateScenePreload()
	{
		sceneLoad = Application.LoadLevelAsync(nextScene);
		state = State.Load;
	}

	// load the scene and show load progress
	private void UpdateSceneLoad()
	{
		if(sceneLoad.isDone == true)
		{
			//sceneLoad = null; // ?
			state = State.Unload;
		}
		else 
		{
			// show progress
		}
	}

	private void UpdateSceneUnload()
	{
		if(resourceUnload == null)
		{
			resourceUnload = Resources.UnloadUnusedAssets();
		}
		else
		{
			if(resourceUnload.isDone == true)
			{
				resourceUnload = null;
				state = State.Post;
			}
		}
	}

	private void UpdateScenePost()
	{
		currentScene = nextScene;
		state = State.Ready;
	}

	private void UpdateSceneReady()
	{
		System.GC.Collect(); // dont use if you need loaded assets that are initially unused
		state = State.Run;
	}

	private void UpdateSceneRun()
	{
		if(currentScene != nextScene)
		{
			state = State.Reset;
		}
	}

	public void OnDestroy()
	{
		if(updateDelegates != null)
		{
			for(int i = 0; i < (int)State.Count; i++)
			{
				updateDelegates *= null;*

  •  	}*

  •  	updateDelegates = null;*

  •  }*

  •  if(manager != null)*

  •  {*

  •  	manager = null;*

  •  }*

  • }*
    }

[1]: Architecting Games in Unity | Rus SCAMMELL - YouTube

2

You never instantiate updateDelegates so it’s null by default and all your updateDelegates[(int)State.Reset] calls fail.
You need to add this code somewhere:

updateDelegates = new UpdateDelegate[State.Count];

But not knowing what State actually is it’s hard to say that this code will work.