如何将一串string字符串转换成CookieCollection

if (response.GetType() == typeof(HttpWebResponse))
{
if(response.Headers["Location"] != null)
{

cookieContainer.Add(response.ResponseUri, GetAllCookiesFromHeader(response.Headers["Set-Cookie"], response.ResponseUri.Host));

HttpWebRequest req = (HttpWebRequest)WebRequest.Create(response.Headers["Location"]);
req.Method = "GET";
req.AllowAutoRedirect = false;
req.CookieContainer = cookieContainer;
req.UserAgent = userAgent;
req.Timeout = timeout;
req.Accept = accept;
return GetWebResponse(req);
}