[local_auth] Support for `macOS` platform

[OutdatedGuy]

Use case

The local_auth plugin currently supports only android, ios and windows platform. It would be great to have support for macOS as well.

Proposal

We can copy the implementation of local_auth_ios and make necessary and proprietary changes to support macOS platform.

[stuartmorgan-g]

We can copy the implementation of local_auth_ios

We don't copy implementations, since that would require maintaining two copies forever; instead we share them. See path_provider, shared_preferences, and video_player for some examples.

The first step in adding macOS support would be renaming the existing iOS package. Normally we use the name of the shared implementing framework; unfortunately in this case that's the LocalAuthentication framework, which would make the name local_auth_localauthentication. Given that I think we'll want to fall back to the less accurate, but more useful in distinguishing the implementation packages, local_auth_darwin.

(For anyone interested in doing this, renaming needs to be done in its own PR, without any macOS additions, and then adding macOS would be a follow-up PR once the rename has landed.)

[stuartmorgan-g]

Normally we use the name of the shared implementing framework; unfortunately in this case that's the LocalAuthentication framework, which would make the name local_auth_localauthentication. Given that I think we'll want to fall back to the less accurate, but more useful in distinguishing the implementation packages, local_auth_darwin.

/cc @jmagman in case you have any alternate thoughts for our latest installment of "Name That Shared iOS/macOS Code!" 🙂.

[OutdatedGuy]

We can copy the implementation of local_auth_ios

We don't copy implementations, since that would require maintaining two copies forever; instead we share them. See path_provider, shared_preferences, and video_player for some examples.

The first step in adding macOS support would be renaming the existing package iOS. Normally we use the name of the shared implementing framework; unfortunately in this case that's the LocalAuthentication framework, which would make the name local_auth_localauthentication. Given that I think we'll want to fall back to the less accurate, but more useful in distinguishing the implementation packages, local_auth_darwin.

(For anyone interested in doing this, renaming needs to be done in its own PR, without any macOS additions, and then adding macOS would be a follow-up PR once the rename has landed.)

Hi, I don't quite understand what you mean. Can you elaborate more on this statement with a simple explanation.

[stuartmorgan-g]

I'm not sure what elaboration you are looking for. Which part isn't clear?

[OutdatedGuy]

The first step in adding macOS support would be renaming the existing iOS package. Normally we use the name of the shared implementing framework; unfortunately in this case that's the LocalAuthentication framework, which would make the name local_auth_localauthentication. Given that I think we'll want to fall back to the less accurate, but more useful in distinguishing the implementation packages, local_auth_darwin.

I didn't understand what you are telling me to do

[stuartmorgan-g]

I'm not telling you to do anything; what you choose to contribute is entirely up to you. I'm describing what we would accept for adding an endorsed macOS implementation of local_auth, which is a single package containing the shared iOS and macOS implementation.

The process for getting from the current state to that state is at least three separate PRs:

1. Rename local_auth_ios to something more generic, as described above.
2. Add macOS support to that renamed package.
3. Switch local_auth to using the new package instead of local_auth_ios.

The relative order of 2 and 3 isn't particularly important, but 1 must be done first.