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[louischan-oursky]

When enabling biometric, always use deviceOwnerAuthenticationWithBiometrics and set localizedFallbackTitle to an empty string to hide the fallback. The rationale is that we want to make sure the device owner can unlock with biometric. If we allowed to use fallback, we do not have such proof.

When authenticating with biometric, allow the developer to use either deviceOwnerAuthenticationWithBiometrics or deviceOwnerAuthentication. When deviceOwnerAuthenticationWithBiometrics is used, set localizedFallbackTitle to an empty string to hide the fallback.

Reference:

• https://developer.apple.com/documentation/localauthentication/lapolicy/deviceownerauthenticationwithbiometrics
• https://developer.apple.com/documentation/localauthentication/lacontext/1514183-localizedfallbacktitle