定时器，延时函数

做游戏开发一定会经常用到延时执行函数，使用Invoke或者协程均可解决问题，不过如果频繁大量使用到延时，所有延时都放在一个monobihavior去做延时比较高效

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

namespace Utility.Common
{
	public class CallbackItem
	{
		public int id;
		public int loopCount;
		public bool useRealtime;
		public float interval;
		public float tmLast;
		public Action callback;
	}
	
	public class TimerHelper : MonoSingleton<TimerHelper>
	{
		private int m_id;
		private List<CallbackItem> m_itemList;

		public TimerHelper ()
		{
			m_id = 0;
			m_itemList = new List<CallbackItem> ();
		}
		
		public int AddCallback (float interval, int loopCount, bool useRealtime, Action callback)
		{
			CallbackItem item = new CallbackItem ();
			item.id = ++m_id;
			item.loopCount = loopCount;
			item.interval = interval;
			item.useRealtime = useRealtime;
			item.callback = callback;

			if (useRealtime)
				item.tmLast = Time.realtimeSinceStartup;
			else
				item.tmLast = Time.time;

			m_itemList.Add (item);
			return m_id;
		}
			
		public int AddCallback (float delay, Action callback)
		{
			return this.AddCallback (delay, 1, false, callback);
		}

		public bool RemoveCallback (int id)
		{
			for (int i = 0; i < m_itemList.Count; ++i) {
				if (m_itemList [i].id == id) {
					m_itemList.RemoveAt (i);
					return true;
				}
			}
			return false;
		}

		private void Update ()
		{
			float tm = Time.time;
			float tmReal = Time.realtimeSinceStartup;
			float tmCur = 0;
			CallbackItem itemRef = null;

			for (int i = m_itemList.Count - 1; i >= 0; --i) {
				if (m_itemList.Count <= i)
					break;

				itemRef = m_itemList [i];

				tmCur = itemRef.useRealtime == true ? tmReal : tm;
				if (tmCur - itemRef.tmLast >= itemRef.interval) {
					itemRef.tmLast = tmCur;

					if (itemRef.callback != null)
						itemRef.callback ();

					if (itemRef.loopCount > 0)
						--itemRef.loopCount;
					if (itemRef.loopCount == 0)
						m_itemList.RemoveAt (i);
				}
			}
		}
	}
}