Xamarin Azure AD B2C登录，卡在登录页面

Question

I am attempting to log into a xamarin mobile application using AAD B2C authentication. I have created the solution in visual studio. In Azure I have created my tenant, registered a native application and a web application (Properties below) and am trying to debug my application. Currently, I am redirected to the B2Clogin page and can enter a username and password. Then it processes the request and stays on that page indefinitely. When I check the azure portal, I can see the account I created through the B2C login page and I can see successful sign-ins but the B2C login page does not redirect back to my application. I'm also using AuthenticationContinuationHelper in AppDelegate.cs as well as in MainActivity.cs

In App.cs

````
     public static string B2CClientEndpoint = "<UserFlowAuthorizationEndpoint>"; //the endpoint generated when we ran the user flow.
            public static string[] B2CScopes = { "<RegisteredWebAPI.Read>" };

       PCAB2C = PublicClientApplicationBuilder.Create(B2CClientID)
                    .WithB2CAuthority("https://<DirectoryName>.b2clogin.com/tfp/<DirectoryName>.onmicrosoft.com/<Policy>")
                    .WithIosKeychainSecurityGroup("<SecurityGroup>")
                    .WithRedirectUri("msal<ApplicationID>://auth")
                    .Build();

````

In Controller class

````C#

     IAccount User = Accounts.FirstOrDefault();
                    if (Accounts.Count() != 0)
                    {
                        Result = await App.PCAB2C.AcquireTokenSilent(App.B2CScopes, User)
                       .WithB2CAuthority("<B2CSignInAuthority>")
                       .ExecuteAsync();
                    }
                    else
                    {
                        User = Accounts.FirstOrDefault();
                        Result = await App.PCAB2C.AcquireTokenInteractive(App.B2CScopes)
                            .WithB2CAuthority("<B2CSignInAuthority>")
                            .WithParentActivityOrWindow(App.ParentWindow)
                            .WithAccount(User)
                            .ExecuteAsync();
                    }

```

Answer 1

According to the official documentation of AD B2C,

To refresh and get tokens in a hidden iframe, use prompt=none to ensure that the iframe does not get stuck on the sign-in page, and returns immediately.

So essentially, verify your URL and don't forget to review the Error response!

Answer 2

I've had this problem and resolved it by reducing the minimum target Android & iOS versions.

ie: Android 8.0 and higher & iOS min 13.0

Apparently, MSAL has a min OS version to target in Xamarin Forms builds.