Hi! Let's say I have kotlin data class `data class...

# kotlin-native

[sngrekov]

Hi! Let's say I have kotlin data class
data class DataClassTest(val foo: String = "foo", val bar : Int = 1)

So in kotlin code I can initialize it with default properties like
DataClassTest(foo = "bar")
But when I try to use it the same way in swift
DataClassTest(foo : "bar")
I get an error "Cannot invoke initializer for type 'DataClassTest' with an argument list of type '(foo: String)'"

Am I missing something?

[russhwolf]

Similar to Java interop, Swift does not see Kotlin's default parameter values

[sngrekov]

This is sad( Is by design or just a missing implementation? Swift's default initializers are look very similar to Kotlin's default parameters..

[sngrekov]

K/N interop page has this statement

Kotlin constructors are imported as initializers to Swift/Objective-C.

So, in this context default args != initializers, correct?

[russhwolf]

Initializers there means init() methods in Swift/Obj-C

[russhwolf]

For default parameters, I think it's because Obj-C doesn't have them, so Kotlin doesn't see them. Kotlin's Swift interop is only through Obj-C.

[sngrekov]

Initializers there means init() methods in Swift/Obj-C

ah, thanks, good to know

[sngrekov]

For default parameters, I think it's because Obj-C doesn't have them, so Kotlin doesn't see them. Kotlin's Swift interop is only through Obj-C.

Interesting.. That means we wont get any Kotlin goodies that ObjC doesn't have?

[olonho]

not exactly, more correct would be statement that in Kotlin code visible to Swift only mechanisms available in Objective-C interop could be present (note, for example, swift_name attribute in generated headers)

[sngrekov]

Thanks Nikolay! Where can I read/watch more about this interop inner kitchen since official /objc_interop.html page doesn't go into much details..

[loganj]

so, Java doesn’t get default parameters either, but @JvmOverloads is a thing

[loganj]

any prospect of similar approaches for objc/swift interop?

[svyatoslav.scherbina]

Similar approach can eventually become available.