Request: Swift Package Manager support

[amomchilov]

Would you be interested in making this repo compatible with the Swift Package Manager?

I don't mind doing it and making a PR, if there's interest.

[CodaFi]

Sure! I'm not sure what the look and feel of these APIs is when they're imported in Swift, but if you're up to it I'd certainly appreciate the contribution.

[avaidyam]

@CodaFi You'll need to mark things with __Nullable and __Nonnull for starters, and I believe you can create a package overlay via NS_SWIFT_NAME pretty easily to transform it into a struct or class-like interface.

[CodaFi]

Determining nullability for this API surface is going to be a painful slog, I can feel it...

[avaidyam]

@CodaFi Yeah, not to mention you can't produce correct Swift throws overlays because of the return type. I don't know how to correct that one unfortunately.

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Also, I remember you from the TwUI days... hello again! 👋

[CodaFi]

None of these functions should ever throw a catchable exception. Not only would it have violated an invariant across a MIG’ed interface, it would be bubbling up from across at least one framework boundary.

I think we’re going to need APINotes here too. NS_SWIFT_NAME is only fine in the small.

[avaidyam]

Well, I would see it as the CGError being returned would instead be caught or ignored by a try? or so. And your suggestion of APINotes is probably more correct - I was thinking of just wrapping the functions in an ObjC class and letting Swift auto-import that but it causes some unwanted (and un-needed) overhead.

[CodaFi]

The few CGError-returning public APIs I can find don't import as throwing. Do you have an example of what you had in mind?

[avaidyam]

Right - I was suggesting having them import as throwing instead. i.e. CGError CGSDoSomething(...) would import as func CGSDoSomething(...) throws.