hmm technically you could find a way to configure gradle properly, but it would fall outside the KMP magic.
KMP projects do have the Foundation library available in iosMain by default. You can add any dependencies that are compatible with Objective-C as well.
https://kotlinlang.org/docs/multiplatform-mobile-ios-dependencies.html
So, you shouldn't have to write a swift class in iosMain library just because you want access to some platform specific API. Not sure what your use case is, but there's probably a KMP way to do it without having to write swift outside of your proper ios module