A pause manager for Unity

PauseManager.cs

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

public enum PauseManagerState
{
	Pausing,
	UnPausing,
	Idle,
	Paused
}

public sealed class PauseManager : MonoBehaviour 
{
	[SerializeField] 
	private bool m_dontDestroyOnLoad;

	private PauseManagerState m_state;
	private float m_lastTimeScale;
	private bool m_hardPause;
	private static PauseManager m_instance;
	
	public static PauseManagerState State
	{
		get
		{
			return m_instance != null ? m_instance.m_state : PauseManagerState.Idle;
		}
	}
	
	public static bool IsPaused
	{
		get
		{
			return m_instance != null ? (m_instance.m_state == PauseManagerState.Paused) : false;
		}
	}
	
	public static bool Exists
	{
		get { return m_instance != null; }
	}
	
	public static void Pause()
	{
		if(m_instance != null)
		{
			//	The game will be paused at the start of the next update cycle.
			if(m_instance.m_state == PauseManagerState.Idle)
			{
				m_instance.m_state = PauseManagerState.Pausing;
			}
		}
	}
	
	public static void UnPause()
	{
		if(m_instance != null)
		{
			//	The game will be unpaused at the start of the next update cycle.
			if(m_instance.m_state == PauseManagerState.Paused)
			{
				m_instance.m_state = PauseManagerState.UnPausing;
			}
		}
	}
	
	private void Awake()
	{
		if(m_instance != null)
			Debug.LogWarning("You shouldn't have more than one instance of PauseManager");

		m_instance = this;
		m_hardPause = false;
		m_lastTimeScale = Time.timeScale;
		m_state = PauseManagerState.Idle;
		if(m_dontDestroyOnLoad)
			DontDestroyOnLoad(gameObject);
	}
	
	private void Update()
	{
		switch(m_state)
		{
		case PauseManagerState.Pausing:
			m_lastTimeScale = Time.timeScale;
			m_state = PauseManagerState.Paused;
			Time.timeScale = 0.0f;
			break;
		case PauseManagerState.UnPausing:
			m_state = PauseManagerState.Idle;
			Time.timeScale = m_lastTimeScale;
			break;
		default:
			break;
		}
		
		if(Input.GetButtonDown("Pause"))
		{
			if(m_state == PauseManagerState.Idle)
			{
				m_state = PauseManagerState.Pausing;
				m_hardPause = true;
			}
			else if(m_state == PauseManagerState.Paused)
			{
				if(m_hardPause)
				{
					m_state = PauseManagerState.UnPausing;
					m_hardPause = false;
				}
			}
		}
	}
	
	private void OnLevelWasLoaded()
	{
		if(m_state != PauseManagerState.Idle)
		{
			Time.timeScale = m_lastTimeScale;
			m_state = PauseManagerState.Idle;
		}
	}
}