主要功能

用C#实现的Coroutine，使用方式类似于Unity的Coroutine。核心原理是利用了C#提供的迭代器  

协程类

CustomYieldInstruction：接口类，需要继承它
WaitForSeconds：按秒等待
WaitForFrames：按帧数等待
WaitUntil：等待条件成立，跳到下一个迭代器
WaitWhile：与WaitUntil相反，等待条件不成立时跳到下一个迭代器

使用方式举例

class Client
{
    private static Coroutine _coroutine;
    private static int _currFrame = 0;
    static void Main(string[] args)
    {
        _coroutine = new Coroutine();
        _coroutine.StartCoroutine(WaitForFrames());
        _coroutine.StartCoroutine(WaitForSeconds());
        _coroutine.StartCoroutine(WaitUntil());
        _coroutine.StartCoroutine(WaitWhile());
        _coroutine.StartCoroutine(YieldBreak());
        _coroutine.StartCoroutine(YieldReturnNull());

        while (true)
        {
            _currFrame++;
            _coroutine.Tick();
            Thread.Sleep(1);
        }
    }
    private static IEnumerator WaitForFrames()
    {
        Console.WriteLine("WaitForFrames:" + _currFrame);
        yield return new WaitForFrames(3);
        Console.WriteLine("WaitForFrames:" + _currFrame);
        yield return new WaitForFrames(3);
        Console.WriteLine("WaitForFrames:" + _currFrame);
    }
    private static IEnumerator WaitForSeconds()
    {
        Stopwatch stopwatch = new Stopwatch();
        stopwatch.Start();
        Console.WriteLine("WaitForSeconds:" + stopwatch.ElapsedMilliseconds * 0.001f);
        yield return new WaitForSeconds(3);
        Console.WriteLine("WaitForSeconds:" + stopwatch.ElapsedMilliseconds * 0.001f);
        yield return new WaitForSeconds(3);
        Console.WriteLine("WaitForSeconds:" + stopwatch.ElapsedMilliseconds * 0.001f);
    }
    private static IEnumerator WaitUntil()
    {
        Console.WriteLine("WaitUntil:" + _currFrame);
        yield return new WaitUntil(()=> _currFrame == 10);
        Console.WriteLine("WaitUntil:" + _currFrame);
    }
    private static IEnumerator WaitWhile()
    {
        Console.WriteLine("WaitWhile:" + _currFrame);
        yield return new WaitWhile(() => _currFrame < 10);
        Console.WriteLine("WaitWhile:" + _currFrame);
    }
    private static IEnumerator YieldBreak()
    {
        Console.WriteLine("Start YieldBreak");
        yield break;
        Console.WriteLine("End YieldBreak");
    }
    private static IEnumerator YieldReturnNull()
    {
        Console.WriteLine("YieldReturnNull:" + _currFrame);
        yield return null;
        Console.WriteLine("YieldReturnNull:" + _currFrame);
        yield return null;
        Console.WriteLine("YieldReturnNull:" + _currFrame);
    }
}