coins App stocks their story of adopting KMM and cashing in on shared code throughout their cellular

cash App is the perfect way to ship money, spend money, shop cash, and buy cryptocurrency. We believe in imparting every body with get right of entry to to vital financial services so that it

The app has been constructed with the native Android/iOS toolchains throughout, with a few small exceptions. We delivered a JavaScript runtime to energy some shared server-driven logic for showing sensitive charge statistics, and that changed into our first exposure to shared code. We endured to test with JavaScript as a tool for sharing code after 2016, however we concluded that until occasions required it, the price of running with JavaScript outweighed the price of sharing code. we strive for a fast development turnaround with small pull requests which are reviewed and merged in a count of hours, and working with JavaScript continually slowed us down, each within the writing and the reviewing of it. over the years our Android and iOS groups grew nearer, the platforms did the identical with speedy and Kotlin, and collaboration among the two teams bolstered. We started bouncing thoughts off every other and evaluating code, and comparable implementations began emerging within the codebase.

The selection to test out Kotlin Multiplatform started in open supply. A library we maintain known as SQLDelight changed into gearing as much as generate Kotlin-best APIs, and the decision turned into made to also use KMM to make the ones generated APIs platform-agnostic. The fit appeared herbal. due to the fact SQLite is the most extensively used pass-platform era around, this would function an possibility to check the technology, and it'd open the doors for coins App to apply it later, since the Android version of the app relied heavily at the library at its middle.

within cash App the fee proposition of the usage of KMM was twofold: we should get rid of some of the shared JavaScript that become inflicting issues and allow the Android and iOS engineers to take the subsequent step in their collaboration and hold a single codebase. We cherished the "shared commercial enterprise, local UI" concept that Kotlin Multiplatform promoted, and it meant that our groups did no longer need to surrender the use of their desired toolchains. We started testing the technology within cash App in 2018 with the assist of TouchLab, slowly rolling it out in the back of a function flag to make certain we should roll again and upstream our issues to JetBrains if we encountered any early-adopter problems.

within the final 12 months, we’ve made most important modifications to how we use Kotlin Multiplatform to help teams to adopt it. We had at the start brought the Gradle toolchain to the iOS build through preserving the shared code within the same repository, but the delivered value of going for walks Gradle and rebuilding the task did no longer make experience in mild of how frequently the dependency became being changed. instead, we created a shared repository for Android/iOS to be the home for our shared enterprise good judgment. considering that then, our network, investing, and boom teams have all built functions with components of their commercial enterprise good judgment in KMM. What has made me most proud is that the contributions have come now not only from Android and iOS team members, however from the server team as nicely! on account that we use Kotlin for our server-aspect development, their crew is now able to paintings within the repository, and due to the fact the platform-agnostic Kotlin so closely resembles speedy that the shift is possible for our iOS group too.

further to using SQLDelight, we use CrashKiOS from TouchLab to get better stack strains in the wild, and we are within the process of adopting wire to paintings with protocol buffers within the shared codebase. As for which elements of our commercial enterprise logic we’ve advocated KMM as a solution for, we’ve had the maximum achievement so far with patience and pure functions inside the shared code, and subsequent we’re hoping to paintings greater intently with our network APIs the use of wire.

The enormous majority of our code is written natively �" developer happiness and productivity remains the most critical thing for us, and our consciousness right now's making sure folks who need to attempt Kotlin Multiplatform can achieve this without difficulty (and the wide variety of individuals who do is developing!). The trend in the final year of more tasks exploring it as an alternative shows the power of the generation. With JavaScript, we had been brief to run away after giving it a shot, but to this point more and more folks at the group have been showing hobby in adopting KMM.