Swift interoperability with category on NSLocale

Question

I have a mixed Swift/Objective-C project with a category on NSLocale defining (among others):

- (NSString*)extendedLanguageCode;

I used to access this method in Swift like this:

Locale.current.extendedLanguageCode()

In Xcode 8 beta 4 this no longer works and I have to cast Locale back to NSLocale:

(Locale.current as NSLocale).extendedLanguageCode()

Is this the intended behavior? If yes, I don't like it!

662

Posted by

ortwin

Reply

Answer 1

I'd be fine to simply use NSLocale in Swift but this doesn't work either:

Right.

NSLocale.current

is returning a value of type

Locale

, which is a bit strange but there you go (-:

If I'd convert my NSLocale category to a Swift extension to Locale, can I then still use it from Objective-C code as NSLocale?

No. As I mentioned earlier, they are two separate types. However, you can have your Swift code call your Objective-C very easily.

extension Locale {
    var extendedLanguageCode: String {
        return (self as NSLocale).extendedLanguageCode()
    }
}

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Apple Developer Relations, Developer Technical Support, Core OS/Hardware

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Posted by

eskimo

Answer 2

Yes, that’s expected behaviour.

Locale

and

NSLocale

are separate types and thus a category on one doesn’t translate to an extension on the other.

Why don’t you add your own Swift extension to

Locale

?

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Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Posted by

eskimo

Answer 3

I'd be fine to simply use NSLocale in Swift but this doesn't work either:

NSLocale.current.extendedLanguageCode()

fails with "Value of type 'Locale' has no member extendedLanguageCode". So Swift seems to translate NSLocale to Locale behind the scenes.

If I'd convert my NSLocale category to a Swift extension to Locale, can I then still use it from Objective-C code as NSLocale?

Posted by

ortwin

Answer 4

I'd be fine to simply use NSLocale in Swift but this doesn't work either:

Right.

NSLocale.current

is returning a value of type

Locale

, which is a bit strange but there you go (-:

If I'd convert my NSLocale category to a Swift extension to Locale, can I then still use it from Objective-C code as NSLocale?

No. As I mentioned earlier, they are two separate types. However, you can have your Swift code call your Objective-C very easily.

extension Locale {
    var extendedLanguageCode: String {
        return (self as NSLocale).extendedLanguageCode()
    }
}

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

Posted by

eskimo

Accepted Reply