Face ID on iPhone X

Question

LABiometryType property is set only when canEvaluatePolicy succeeds for a biometric policy.

How to identify touch id or face id is available on device before enrolling? We want to show a message in app to user ie "Enroll touch id" or "Enroll face id" if the device is not enrolled yet. We do not want put any device specific code.

Answer 1

You can't tell before you try to enroll.

You should design your app so a user first authenticates with your fallback mechanism (assuming it's not just the PIN, but something like user/pwd) and then you call canEvaluatePolicy to ask them to enroll after that succeeds. If that doesn't fail with a -6 (not supported on device) error, then store a flag indicating that it's supported on the device. Configure your UI and login flow based on that stored setting.