CookieExtensions.cs

using System.Collections.Generic;

// ReSharper disable once CheckNamespace
namespace System.Web.Mvc
{
    public static class CookieExtensions
    {
        /// <summary>
        /// Creates a cookie if it doesnt exists and gets the item if it exists
        /// </summary>
        /// <param name="html"></param>
        /// <param name="cookieName"></param>
        /// <param name="itemkey"></param>
        /// <returns></returns>
        public static string GetCookieValue(this HtmlHelper html, string cookieName, string itemkey)
        {
            return GetCookie(html.ViewContext.HttpContext,cookieName).Values[itemkey];
        }

        /// <summary>
        /// Creates a cookie if it doesnt exists and sets the item
        /// </summary>
        /// <param name="context"></param>
        /// <param name="cookieName"></param>
        /// <param name="itemkey"></param>
        /// <param name="value"></param>
        public static void SetCookieValue(this HttpContextBase context, string cookieName, string itemkey, string value)
        {
            GetCookie(context, cookieName).Values[itemkey] = value;
        }

        public static void RemoveCookieValue(this HttpContextBase context, string cookieName, string itemkey)
        {
            GetCookie(context, cookieName).Values.Remove(itemkey);
        }

        /// <summary>
        /// Creates a cookie if it doesnt exists and gets the item if it exists
        /// </summary>
        /// <param name="context"></param>
        /// <param name="cookieName"></param>
        /// <param name="itemkey"></param>
        /// <returns></returns>
        public static string GetCookieValue(this HttpContextBase context, string cookieName, string itemkey)
        {
            return GetCookie(context, cookieName).Values[itemkey];
        }

        /// <summary>
        /// Creates a cookie if it doesnt exists and sets the item
        /// </summary>
        /// <param name="html"></param>
        /// <param name="cookieName"></param>
        /// <param name="itemkey"></param>
        /// <param name="value"></param>
        public static void SetCookieValue(this HtmlHelper html, string cookieName, string itemkey, string value)
        {
            GetCookie(html.ViewContext.HttpContext, cookieName).Values[itemkey] = value;
        }

        public static void RemoveCookieValue(this HtmlHelper html, string cookieName, string itemkey)
        {
            GetCookie(html.ViewContext.HttpContext, cookieName).Values.Remove(itemkey);
        }

        private static HttpCookie GetCookie(HttpContextBase context, string cookieName)
        {

            //see if we have the cookie in the cookielist
            var cookie = context.Request.Cookies.Get(cookieName);
            if (cookie != null)
            {
                return cookie;
            }
            cookie = new HttpCookie(cookieName);
            context.Request.Cookies.Set(cookie);
            return cookie;
        }

        /// <summary>
        /// Saves any changed or new cookies
        /// </summary>
        /// <param name="html"></param>
        /// <param name="expireDateTime">Default will be 1 year from now</param>
        public static void SaveCookies(this HtmlHelper html, DateTime? expireDateTime = null)
        {
            html.ViewContext.HttpContext.SaveCookies(expireDateTime);
        }

        /// <summary>
        /// Save a cookie if it was changed, or newly created
        /// </summary>
        /// <param name="html"></param>
        /// <param name="cookieName"></param>
        /// <param name="expireDateTime">Default will be 1 year from now</param>
        public static void SaveCookie(this HtmlHelper html, string cookieName, DateTime? expireDateTime = null)
        {
            html.ViewContext.HttpContext.SaveCookie(cookieName,expireDateTime);
        }

        /// <summary>
        /// Saves any changed or new cookies
        /// </summary>
        /// <param name="context"></param>
        /// <param name="expireDateTime">Default will be 1 year from now</param>
        public static void SaveCookies(this HttpContextBase context, DateTime? expireDateTime = null)
        {
            // adding a cookie to the response, also adds it again to the request this is why we use a buffer
            List<HttpCookie> cookielist = new List<HttpCookie>();

            // add all cookies to the buffer
            for (int i = 0; i < context.Request.Cookies.Count; i++)
            {
                var cookie = context.Request.Cookies[i];
                cookie.Expires = expireDateTime ?? DateTime.Now.AddYears(1);
                cookielist.Add(cookie);
            }

            // remove from request and add to response (which would double add it to the request)
            foreach (var cookie in cookielist)
            {
                context.Request.Cookies.Remove(cookie.Name);
                //context.Response.Cookies.Set(cookie);
                SetResponseCookie(context, cookie, expireDateTime);
            }
        }

        /// <summary>
        /// Save a cookie if it was changed, or newly created
        /// </summary>
        /// <param name="context"></param>
        /// <param name="cookieName"></param>
        /// <param name="expireDateTime">Default will be 1 year from now</param>
        public static void SaveCookie(this HttpContextBase context, string cookieName, DateTime? expireDateTime = null)
        {
            // adding a cookie to the response, also adds it again to the request this is why we use a buffer
            var cookie = context.Request.Cookies.Get(cookieName);
            if (cookie == null)
            {
                return;
            }
            cookie.Expires = expireDateTime ?? DateTime.Now.AddYears(1);
            context.Request.Cookies.Remove(cookie.Name);
            SetResponseCookie(context, cookie, expireDateTime);
        }

        private static void SetResponseCookie(HttpContextBase context, HttpCookie cookie, DateTime? expireDateTime = null)
        {
            if (context == null || cookie == null || string.IsNullOrWhiteSpace(cookie.Name))
            {
                return;
            }
            context.Response.Cookies[cookie.Name].Name = cookie.Name;
            context.Response.Cookies[cookie.Name].Value = cookie.Value;
            context.Response.Cookies[cookie.Name].Expires = expireDateTime ?? DateTime.Now.AddYears(1);
            context.Response.Cookies[cookie.Name].Secure = cookie.Secure;
            context.Response.Cookies[cookie.Name].Domain = cookie.Domain;
            context.Response.Cookies[cookie.Name].Shareable = cookie.Shareable;
        }
    }
}

Usage controller: HttpContext.Current.Request.RequestContext.HttpContext.
Usage razor: Html.