Sometimes you still need to know if Cookie exists in Response. Then you can check if cookie key exists:
HttpContext.Current.Response.Cookies.AllKeys.Contains("myCookie")
More info can be found here.
In my case I had to modify Response Cookie in Application_EndRequest method in Global.asax. If Cookie doesn’t exist I don’t touch it:
string name = "myCookie";
HttpContext context = ((HttpApplication)sender).Context;
HttpCookie cookie = null;
if (context.Response.Cookies.AllKeys.Contains(name))
{
cookie = context.Response.Cookies[name];
}
if (cookie != null)
{
// update response cookie
}