Hi I want to create a Swift class and use it in Kotlin in io

Question

Hi I want to create a Swift class and use it in Kotlin in iosMain Can I just create both files in iosMain or do I need to do some extra steps

kpgalligan · Answer

If you want to literally write swift and have it available to Kotlin it s much more involved You ll need to put it in a folder that you can compile and make available somehow It ll need to be exported to Objective C with ` objc` see here <https kotlinlang org docs native objc interop html> Then you ll need to wire up cinterop from the Kotlin side to make the Swift class visible to Kotlin Then you ll need to figure out how to package all of that up

kpgalligan · Answer

Summary it s uncommon and non trivial We re looking at ways to include generated Swift in the Kotlin framework package but that s just to help adapt Kotlin to Swift

Tiago Nunes · Answer

Thanks I ll try and do that My use case is very specific I need to use AWS Amplify with KMM The Amplify framework generates classes in both Java and Swift They said they won t bet on KMM because they re betting on Flutter so I can t have the classes generated in KMM So what I m doing is mapping the Java classes to KMM compatible classes in an automatic way I was going to do the same for the Swift classes but I need to have access to these classes from Kotlin

Tiago Nunes · Answer

Though I thought I saw in some sample somewhere swift files inside of iosMain

Kris Wong · Answer

kotlin source sets expect kotlin source code you would need to add your generated swift files to a library with an objective c bridging header in order to use C interop to add it as a dependency to the iOS target

kpgalligan · Answer

Swift inside iosMain would be pretty great if that was automatic although I could see that being problematic dependencies etc There s definitely some plumbing involved here but assuming the Swift is Objc compatible it should work

kpgalligan · Answer

They said they won t bet on KMM because they re betting on Flutter That s an odd official position to take but OK

Tiago Nunes · Answer

Tiago Nunes · Answer

I meant a AWS engineer said something like that on StackOverflow

kpgalligan · Answer

Yeah I assumed an AWS engineer said that Just an odd position especially reading what he wrote The Amplify team is currently investing in Flutter as a multi platform offering then later As a final note the Amplify products are intended as a front end framework Therefore it s unlikely that we we ll ever prioritize a full multi platform build

Tiago Nunes · Answer

Having the swift files with objc in a cocoapods library I can use the cocoapods plugin instead of cinterop right

Kris Wong · Answer

yes cocoapods plugin uses cinterop

Kris Wong · Answer

but dependencies between pods is not supported at this time so if your pod depends on a pod from amazon that s not supported

Kris Wong · Answer

or rather if the API of your pod depends on classes from another pod

Tiago Nunes · Answer

Oh okay That s a problem My library depends on an Amplify pod

Kris Wong · Answer

Tiago Nunes · Answer

But if I use cinterop I have the same problem right My library depends on the Amplify pod so it won t work

Kris Wong · Answer

correct

Kris Wong · Answer

if your module doesn t use import you might be able to get it working

Kris Wong · Answer

all the details are on the issue

Tiago Nunes · Answer

I ll take a look thanks slightly smiling face

Tiago Nunes · Answer

Hm I think the Amplify pod is written in Swift and doesn t have objc headers That s probably a roadblock huh

Kris Wong · Answer

yes cinterop doesn t support swift

Kris Wong · Answer

though if you re not using those APIs directly from Kotlin it s not necessarily a roadblock

Kris Wong · Answer

if you have your own framework that covers the entire API and has obj c bridging then you should be OK

Tiago Nunes · Answer

That s the plan