[Auth]: Evaluate `Auth.auth().canHandle(_ url: URL) -> Bool` in a scene delegate context

[ncooke3]

This is not a breaking change. Added to milestone 12 for reassessment if not address beforehand.

Description

Auth's canHandle(_ url: URL) API doesn't fit as well in the scene delegate world as it does in the app delegate world. In the app delegate of the below scene delegate method, a boolean needs to be returned to the API returns a Bool. That doesn't make sense in the scene delegate world (see below delegate method's lack of return type).

Two approaches:

• Add @discardableResult to the API
• Add new API for scene delegate context (e.g. canHandle(_ urlContext: URLContext) -> Void to the API surface

func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
  for urlContext in URLContexts {
      let url = urlContext.url
      _ = Auth.auth().canHandle(url)
  }
}

API Proposal

No response

Firebase Product(s)

Authentication

[ns-vasilev]

@ncooke3, I'd be happy to take on this issue. Is there a deadline, or has it been resolved already?

[ncooke3]

Thanks for taking a look, @ns-vasilev! There is no deadline. I'll take a look at your PR. I think @discardableResult is a reasonable improvement. Long term, I think a new scene delegate specific API may be in order–– something like handle(_ urlContext: URLContext) throws -> Void.

[ns-vasilev]

@ncooke3 Perhaps we could add the new method right away, as you described. What do you think?

[ncooke3]

@ns-vasilev, I think a new API would be more clear than adding @discardableResult to the existing API.

func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
  for urlContext in URLContexts {
      Auth.auth().handleIfNeeded(urlContext.url)
  }
}

I do like how adding @discardableResult is simple and doesn't require a new API, but I worry it makes the usage less clear since canHandle is actually handling the URL if needed.

[ns-vasilev]

@ncooke3 Are you sure the method needs to be marked as throws? How should the error be handled in the scene(_:openURLContexts:) method? Should we log it somewhere?

I've added the method.