Our core "business logic" lives in Rust. This is a shared bit of code between Android & iOS that mainly deals with orchestration, serialization, and server communication. We managed to extract ~1/2 of each platform's native code into this shared orchestration. What's left on each platform is more like a platform driver.
I fully admit that things are different for us because we're not dealing with a bunch of UI that we manage (instead we're dealing with UI that our customers have written in Java/Swift/Objective-C/etc), but I think that there's a few places where we've made this work in a better way:
- We've chosen flatbuffers to serialize most (not all) of the data between the platform drivers and the shared library.
- We're using a language that's a little more hip. It's still not very easy to hire Rust developers, but developers interested in Rust are _very_ interested.
- We built tooling early on to make this pretty seamless. Our Rust code builds in XCode and gradle, so there's no real friction to a developer getting up and running.
Our team is about a year in on this transition to Rust and so far it's helped us move far quicker, especially given the size of our team.