Device nip fallback does not works on iOS 17-18

[spelletier]

Using NuGet package Oscore.Maui.Biometric Version="1.0.1" on device (iPhone 13 pro with iOS 18.1) and simulator (iPhone 15 pro with iOS 17.2), the biometric prompt never ask for the device NIP even after a failed faced attempt.

The sample and code indicate this code should works:

if (await BiometricAuthentication.Current.IsAvailableAsync(AuthenticationStrength.Any))
{
var config = new AuthenticationRequest("Confirmez votre identité", "Pour accéder à vos messages");
config.Strength = AuthenticationStrength.Any;
var authResult = await BiometricAuthentication.Current.AuthenticateAsync(config);
}

The prompts ask for faceid only, it behave like if using LAPolicy.deviceOwnerAuthenticationWithBiometrics instead of LAPolicy.deviceOwnerAuthentication.

My understanding of the source code in this repository is that using config.Strength = AuthenticationStrength.Any should transpose to LAPolicy.deviceOwnerAuthentication but the program execution does not confirm this.

[HavenDV]

Maui.Biometric/src/libs/Maui.Biometric/Platforms/MaciOS/IosBiometricAuthentication.cs

Lines 140 to 147 in ce2c664

	private static LAPolicy GetPolicy(AuthenticationStrength strength)
	{
	return strength switch
	{
	AuthenticationStrength.Any => LAPolicy.DeviceOwnerAuthentication,
	_ => LAPolicy.DeviceOwnerAuthenticationWithBiometrics,
	};
	}

Thanks for raising the issue. Interesting, as it is clearly stated in the code, so it probably needs some research.