Expo LocalAuthentication - No fallback to passcode

Please provide the following:

  1. SDK Version: 34
  2. Platforms(Android/iOS/web/all): iOs
LocalAuthentication.authenticateAsync({ fallbackLabel: '', promptMessage: 'Authenticate' })

Hello guys, I’ve the following doubt:

  • Is it possible to make the TouchID (or FaceID) authentication to not fallback into iOs system passcode?

For security reasons I want only to be able to authenticate through touch or face ID OR making it fallback to a passcode within my app (like Revolut, for example).

From the docs:
fallbackLabel: (...) Setting this option to an empty string disables fallback to device passcode. -> Not working as intended, device passcode still triggering.

Also, when providing options for the authenticateAsync method, authentication modal doesn’t open if only fallbackLabel is provided, needs promptMessage too although docs state no obligation.

Thank you

Hey @amsimoes,

Would you mind creating a Snack that replicates the issue so I can test this on my end?


Cheers @adamjnav,

I’ve found that this issue is due to a native module feature that is missing, see github issue: https://github.com/expo/expo/issues/4799

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