I have a kotlin fun defined in a KMP project with an Int paramter -

fun getUser(userId: Int) {}

However, when I try to use this function in swift, I'm getting a type error -

Cannot convert value of type 'Int?' to expected argument type 'KotlinInt?'

Presumably I'm missing a step or config here? I'd assume that KMP magic handles the Int implementation in each platform without me having to write any additional mapping?

You need to pass the swift type that maps your kotlin type. https://kotlinlang.org/docs/native-objc-interop.html#nsnumber Oh wait, you are using the right type. What if you pass an objective-c integer?

I ended up adding a swift Int extension to handle the conversion, as per this article! https://medium.com/cox-auto-tech-blog/navigating-seas-with-kmm-an-ios-developer-story-3791310e39eb

extension Int {
    /// converts this Integer to KotlinInt
        func toKotlinInt() -> KotlinInt {
            return KotlinInt(integerLiteral: self)
        }
}