Accept self-signed certificate using WWW

We are building an iOS app via Unity. We have a login system that communicates with the client server through the use of the WWW:

 var headers = new Hashtable();
 var url = _rootURL + "/api/auth?username=" + _username + "&password=" + _password; ;
 // Add a custom header to the request.
 // In this case a basic authentication to access a password protected resource.
 headers["Authorization"] = "Basic " + System.Convert.ToBase64String(
                 System.Text.Encoding.ASCII.GetBytes(_username + ":" + _password));
 headers["Accept"] = "application/json";
 
 // Post a request to an URL
 var request = new WWW(url);
 DebugTools.Log("DB - Attempting HTTP Auth...");
 yield return request;
 //.. process results from WWW request here...
 DebugTools.Log("DB - HTTP Auth response recieved...");
 //MW: processing pList response can be disabled as unneccessary for simple server notification requests
             if (request.error != null)
             {
                 //Assume failure to login
                 if (callbackDelegate != null) callbackDelegate(false, "Could not authenticate, please check your internet connection");
                 DebugTools.Log("DB- Http auth error " + request.error);
 
             }

When running this on iOS, it reports : "Http auth error The certificate for this server is invalid. You might be connecting to a server that is pretending to be "your-server.com" "

We had this issue on Android which we solved a different way, but because I can't access the code that handles the networking call after it has been converted to iOS, I need to implement a fix in Unity. I have a physical copy of the server certificate on my machine, I would like to have it bundled with the app and to have the app add it as an exception so that iOS won't complain and (hopefully) I won't need to persist with our Android hack. Does anyone have any pointers?