/// <summary>
        /// Attempt interactive authentication through the broker.
        /// </summary>
        /// <returns>The AuthenticationResult on succes, null otherwise.</returns>
        public async Task <AuthenticationResult> SignInWithPrompt(Activity activity)
        {
            AuthenticationResult result = null;

            try
            {
                Log.Info(_logTagAuth, "Attempting interactive authentication");
                result = await PCA.AcquireTokenInteractive(_scopes)
                         .WithParentActivityOrWindow(activity)
                         .WithUseEmbeddedWebView(true)
                         .ExecuteAsync();
            }
            catch (MsalException e)
            {
                string msg = Resource.String.err_auth + e.Message;
                Log.Error(_logTagAuth, Throwable.FromException(e), msg);
                Toast.MakeText(activity, msg, ToastLength.Long).Show();
                return(null);
            }

            return(result);
        }