How is the shared module of Kotlin Multiplatform Mobile realized on the iOS platform? Is it transpiled to Swift code or how does that work? How performant is it compared to Swift code?
"Kotlin/Native is a technology for compiling Kotlin code to native binaries which can run without a virtual machine. Kotlin/Native includes an LLVM-based backend for the Kotlin compiler and a native implementation of the Kotlin standard library."
When you compile kotlin for iOS, it uses the standard iOS library via bindings, so the performance here is completely native. If, for example, not just syscalls are performed but some calculations: kotlin native is compiled using llvm(not transpiles to swift), as well as swift, which means that the same optimizations will be involved. Also, when interacting with ObjC/Swift, kotlin creates wrappers for its objects containing reference counters (the same as in the ObjC/Swift ARC runtime) which also contributes to a more native interaction.
So yea, it can be faster or slower in some cases, but it's pretty native.