[Bug] iOS broker does not launch on IOS 18.0.1

[stevencreaney]

Library version used

4.65.0

.NET version

8.0.403

Scenario

PublicClient - mobile app

Is this a new or an existing app?

This is a new app or experiment

Issue description and reproduction steps

This is a .Net MAUI app written for Windows/IOS. We are leveraging the sample code provided in the MSAL MAUI sample.

This code previously worked just fine, but until IOS18.0.1 and XCode 16, plus any of the relevant updates from the dotnet workloads and nuget packages, this is now consistent.

When executing AcquireTokenInteractiveAsync on PublicClientApplication, the Task never returns and the application hangs.

return await PublicClientApplication.AcquireTokenInteractive(scopes)
.WithLoginHint(existingAccount?.Username ?? string.Empty)
.WithSystemWebViewOptions(systemWebViewOptions)
.WithParentActivityOrWindow(PlatformConfiguration.Instance.ParentWindow)
.ExecuteAsync()
.ConfigureAwait(false);

The last line of logging is:

False MSAL 4.65.0.0 MSAL.Xamarin.iOS .NET 8.0.10 18.0.1 [2024-10-18 16:06:54Z] Invoking the iOS broker
False MSAL 4.65.0.0 MSAL.Xamarin.iOS .NET 8.0.10 18.0.1 [2024-10-18 16:06:54Z] iOS Broker Payload Count: 16
False MSAL 4.65.0.0 MSAL.Xamarin.iOS .NET 8.0.10 18.0.1 [2024-10-18 16:06:54Z] Starting waiting for broker response

We do see this in the device output:

BUG IN CLIENT OF UIKIT: The caller of UIApplication.openURL(:) needs to migrate to the non-deprecated UIApplication.open(:options:completionHandler:). Force returning false (NO).

We noticed this appears to happen right here:

microsoft-authentication-library-for-dotnet/src/client/Microsoft.Identity.Client/Platforms/iOS/Broker/iOSBroker.cs

Line 210 in 97c51de

private async Task InvokeIosBrokerAsync(Dictionary<string, string> brokerPayload)

Relevant code snippets

return await PublicClientApplication.AcquireTokenInteractive(scopes) .WithLoginHint(existingAccount?.Username ?? string.Empty).WithSystemWebViewOptions(systemWebViewOptions).WithParentActivityOrWindow(PlatformConfiguration.Instance.ParentWindow).ExecuteAsync().ConfigureAwait(false);

Expected behavior

No response

Identity provider

Microsoft Entra ID (Work and School accounts and Personal Microsoft accounts)

Regression

No response

Solution and workarounds

Implement the suggested code updates for UIApplication.open() vs UIApplication.openURL().