public AuthenticationToken CurrentAuthenticationToken()
        {
            String authenticationTokenString = IOSWrapper.IOSFBCurrentAuthenticationToken();

            if (String.IsNullOrEmpty(authenticationTokenString))
            {
                return(null);
            }
            try
            {
                IDictionary <string, string> token = Utilities.ParseStringDictionaryFromString(authenticationTokenString);
                string tokenString;
                string nonce;
                token.TryGetValue("auth_token_string", out tokenString);
                token.TryGetValue("auth_nonce", out nonce);
                return(new AuthenticationToken(tokenString, nonce));
            }
            catch (Exception)
            {
                return(null);
            }
        }