iPhone Biometric (FaceID) do not work in several apps which used same code base. Some notes for Apple Sign-in Flutter.

Some notes for Apple Sign in in Flutter

Recently, Apple Sign-in is implemented at almost apps for some reasons: client requirements, iPhone users' target, enriching sign-in methods, etc. And certainly to us-Flutter developers, Apple Sign-in implementation is the topic we are interested as well.

https://pub.dev/packages/sign_in_with_apple

Many of us are familiar with this awesome dependency. I believe its document is already perfect to be applied and understandable, so there is no any other words for bringing up this problem ( actually I am not going to reduplicate how to use this lib to make my post seems longer 😆).

Some notes for Apple Sign-in

And let’s move on some things you should keep in mind when dealing with Apple Sign-in.

You just have only one opportunity to retrieve user’s apple email.

It was already clearly noted in dependency but I thought there are still some developers (like me 🙄) have skipped this. So I highly raise up this issue such a way to let other one does not silly ask why credential.email after execute SignInWithApple.getAppleIDCredential is always null. ( I thought it would have no one else except me 😵).

For security issue, Apple will only provide email on the first authorization, Up further times, userIdentifierwill be the only data you got when sign-in again, so you should store this data securely and carefully on your server.

Face ID will not work in multiple installed apps if those are built from one code base

In some cases, we need to build a lot of different apps by using one code base. So you will face an issue like: App A, B, and C used 1 code base and installed in device, but just App C works with device Face ID, the others will keep staying at the grey icon below with no detection.

Face ID was freeze with Apple Sign-in

… so for this case, let's create a new XCode Target for it !

Revise how to create XCode Target

Guess you all know about how to duplicate current target.

How to create Target in XCode Flutter

And remember to use the correct Info.plist file for corresponding target.

Update Pod File after that

When you run Flutter project, it will re-run pod install , so if you didn’t change your Pod file to your new Target, its framework will be lost and caused crash after then.

Update

target 'Runner' do
  use_frameworks!
  use_modular_headers!

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

To

def shared_pods
  use_frameworks!
  use_modular_headers!

  flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
end

target 'Runner' do
  shared_pods
end

target 'Runner-Copy' do
  shared_pods
end

Create shared_pods to make sure Pod will apply only one config to all targets you have.

These are some experience in me when playing around Apple Sign-in in Flutter, if you think there is something more interesting, let’s bring up here.

Happy coding!