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

        public async Task<bool> SignInUsingIdentityManager()
        {
            IsSigningIn = true;
            
            // if oauth2 required params are set, register the server for oauth2 authentication.            
            if (App.IsOrgOAuth2)
            {
                var serverInfo = new ServerInfo()
                {
                    ServerUri = App.PortalUri.Uri.ToString(),
                    TokenAuthenticationType = TokenAuthenticationType.OAuthAuthorizationCode,
                    OAuthClientInfo = new OAuthClientInfo() { ClientId = App.AppServerId, RedirectUri = App.AppRedirectUri }
                };
                IdentityManager.Current.RegisterServer(serverInfo);
            }
            // check if a TokenCredential can be retrieved without challenging the user
            else if (IdentityManager.Current.Credentials.Any())
            {  
                try
                {
                    var credential = IdentityManager.Current.Credentials.ElementAt(0) as TokenCredential;                    
                    if (credential != null && !string.IsNullOrEmpty(credential.Token))
                    {
                        // set the credential 
                        _credential = credential;
                        IsSigningIn = false;
                        return true;
                    }
                }
                catch (Exception ex)
                {
                    IsSigningIn = false;
                    var _ = App.ShowExceptionDialog(ex);
                    return false;
                }
            }                                     
            
            // Since a credential could not be retrieved, try getting it by challenging the user
            var credentialRequestInfo = new CredentialRequestInfo
            {
                ServiceUri = App.PortalUri.Uri.ToString(),
                AuthenticationType = AuthenticationType.Token,
            };

            try
            {
                var credential = await IdentityManager.Current.GetCredentialAsync(credentialRequestInfo, true);
                if (credential != null)
                {
                    //set the credential 
                    _credential = credential;
                    IdentityManager.Current.AddCredential(_credential);                    
                    IsSigningIn = false;                    
                    return true;
                }
            }
            catch (Exception ex)
            {
                IsSigningIn = false;
            }

            IsSigningIn = false;
            return false;
        }