But then I think I should use the .o file now on android and configure it in gradle. The scade instructions mentioned by @Finagolfin seam to suggest to make it a jar. I know people have done it just lack a good starting point :) Thanks!
Should I create .so files of an .o file to continue?
No, I haven't seen any docs using my Android SDK bundle, and I have not tried that myself with Swift yet. Invoking native code in an Android app is a fairly straightforward process though of building native shared libraries for each of the architectures you want to support, then calling those methods through JNI. Take a look at this SCADE tutorial I just found through Bing, which gives you an idea of how it's usually done.
@Marc_Prud_hommeaux, do you have any plans with your Skip toolchain to enable uses like this also, ie those who simply want to cross-compile some Swift and use it in their existing app? May be a usecase you want to support also, with some doc or code, not sure.
Skip does support this! While Skip's primary use-case is managing the entire Android application with a mixture of transpiled and natively-compiled Swift, our native toolchain support also enables you to build and package (as an aar file) a separate Android library that you can drop into your existing Android project. It handles exposing your Swift interfaces to Kotlin, as well as provides support for calling back out to Java/Kotlin from the Swift code.
For an overview and walkthrough of this process, check out the Sharing a Swift Model Layer blog post, and further reference the bridging documentation. Questions and feedback welcome, either here or on our Slack!