Declare method unavailable since a specific version of iOS in swift 5

Question

I wish to achieve something like that:

@unavailable(iOS 11.0, *) func oldWay() { ... } @available(iOS 11.0, *) func newWay() { ... }

I've tried things like @available(iOS 11.0, unavailable, *) but it does not compile.

My problem is that I'm conforming to an Objective-C protocol with optional methods. Some of them are only available since iOS 11, my app is available since iOS 10 and I don't want to have both methods implemented for a given platform.

For instance if I do this:

func oldWay() { ... } @available(iOS 11.0, *) func newWay() { ... }

Both methods are implemented on all platforms since iOS 11... That's not what I'm looking for.

So if anyone has an idea...

Would you be better off inheriting from the protocol with your own protocol version written in ObjC? If you did that, seems like you could go macro-crazy, and probably get it to do what you want. — Clay Bridges
– Clay Bridges, Commented Apr 10, 2020 at 14:55

Sweeper · Accepted Answer · 2020-04-10 14:44:56Z

5

You can use the deprecated: argument (and potentially message: as well), because that seems to be what's happening here:

@available(iOS, deprecated: 11.0, message: "Please use 'newWay'") func oldWay() { } @available(iOS 11.0, *) func newWay() { }

This will produce a warning if you try to use the old way. If you want an error instead, replace deprecated with obsoleted.

answered Apr 10, 2020 at 14:44

Sweeper

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6 Comments

Zaphod Over a year ago

I don't want deprecation, but unavailablilty. A deprecated method is still compiled and implemented. Moreover the Objective-C code when testing if a method is implemented has no information on deprecation.

Sweeper Over a year ago

@Zaphod Looking at the generated headers, methods marked with obsoleted look like this - (void)foo SWIFT_AVAILABILITY(ios,obsoleted=11.0);. I don't know much Objective-C, but can't you check for that? To me, this sounds like you need to rewrite the code that "tests if a method is implemented", rather than your Swift code.

Clay Bridges Over a year ago

obsoleted compiles for me, thanks @Sweeper, learned something here. I suggested inheriting the protocol in ObjC above, might be easier.

Zaphod Over a year ago

The Obj-C protocol is not mine, unfortunately. I think the outcome is still different, because when it's not available, you simply does not have the implementation, do you? If you write @available(iOS, unavailable) you won't have it at all in the headers. Besides, I just want the Objective-C method respondsToSelector to return false for this method.

Sweeper Over a year ago

@Zaphod It will still be in the headers even if you write @available(iOS, unavailable). It will appear as - (void)foo SWIFT_UNAVAILABLE;. If you just want respondsToSelector to return false, I guess you could always manually override it... Not a "clean" solution per se, but it should work...

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