ArcGISPortalViewer.Model.PortalService.AttemptAnonymousAccessAsync C# (CSharp) Method

        public async Task AttemptAnonymousAccessAsync()
        {
            var challengeHandler = IdentityManager.Current.ChallengeHandler;
            // Deactivate the challenge handler temporarily before creating the portal (else challengehandler would be called for portal secured by native)
            IdentityManager.Current.ChallengeHandler = new ChallengeHandler(crd => null);  

            try
            {
                var p = await ArcGISPortal.CreateAsync(App.PortalUri.Uri);
                if (p != null)
                {
                    //set the ArcGISPortal
                    Portal = p;
                    SetOrganizationProperties();
                    GalaSoft.MvvmLight.Messaging.Messenger.Default.Send<ArcGISPortalViewer.Helpers.ChangedPortalServiceMessage>(new ArcGISPortalViewer.Helpers.ChangedPortalServiceMessage());
                }
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
            finally
            {
                // Restore ChallengeHandler
                IdentityManager.Current.ChallengeHandler = challengeHandler; 
            }
        }