Our great sponsors
-
KaMPKit
KaMP Kit by Touchlab. A collection of code & tools designed to get your mobile team started quickly w/Kotlin Multiplatform
-
-
WorkOS
The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.
I've been using Kotlin Multiplatform Mobile (KMM) heavily for the past 2 years on my current startup. I'm currently in the process of removing the entire thing.
KMM is an alternative to a cross platform mobile library like Flutter, React Native, etc. The idea is that we could write all of our mobile app's business logic, networking layer, and caching layer in Kotlin, and KMM will codgen the matching iOS code. "We only need to write it once!" is the selling point. Then we get a blank canvas to build our UI using 100% native SwiftUI & Jetpack.
In reality, the codegened iOS code gets you 90% of the way there, the but extra 10% is extremely frustrating to work with. Enums (Sealed Classes in Kotlin) get mangled in translation and you lose exhaustive switch statements. Basic data types like Bool and Int get wrapped so you can only access them using additional .boolValue or Int64(..) constructors. Entire companies are being built around solving the pain point of this last 10%: https://touchlab.co
In my opinion, the fatal mistake the KMM team made was designing it to support Objective-C, instead of just Swift. So you're using a Kotlin layer -> mangled through Objective-C -> accessed from Swift. It's a confusing decision, as the only iOS teams still actively using Objective-C are legacy apps (like the Twitter app), which seems like the opposite target market for new mobile tech like KMM. Kotlin and Swift are both modern languages, and my gut says the interop between the two would be much better without Objective-C in the middle.
Further discussion from Droidcon if you're interested: https://www.droidcon.com/2022/08/01/sdk-design-and-publishin...
> As you progress beyond "POC" to integrating and shipping real production code, the design of the "SDK surface" becomes more complicated and nuanced (or, possibly, problematic)... An Android consumer can see all the richness of the Kotlin language, but the iOS side gets filtered through Objctive-C into Swift. Much can get lost along the way.
