Kotlin Multiplatform in Action

Kotlin Multiplatform - what it is, why you should use it and how to start with it.

Transcript

7. Why share code? • DRY • same code/logic for different platforms • productivity, features, less bugs, more platforms
8. Why share code? • crossplatform in the past • networking library in C • Windows Mobile • Windows • Android • Linux
9. Why share code? • sharing entire components • JVM servers can share business logic with Android apps • All client apps share similar logic and features
11. Why share code? • Mobile platforms share a lot in common
12. Why NOT share code? • Performance • Slower innovation • shared UI • All or nothing • Vendor lock-in • Future • Bugs/lack of features
13. Why use Kotlin Multiplatform? • modern, industrial language • similar to swift, easy for java devs to learn • great tooling, ecosystem and community • open-source • write once, run native everywhere
14. Why use Kotlin Multiplatform? • doesn’t limit you to subset of all platforms • native access to entire platform API from Kotlin • each platform get native, optimized binary • fix bug once, for all platforms • interoperability • optional sharing
15. Why use Kotlin Multiplatform? optional sharing
16. Why not other solutions? • Flutter, React Native, Xamarin • not same usecase • sharing UI - risky • new language, new tools, new libs • accessing platform APIs is hard, bridges • frameworks
18. Why not other solutions? “Anything that requires you to make large decisions and potentially large rewrites, perform large retrainings and rehirings, or anything that has to share UI or doesn’t work well with a native platform is, well, very risky.” - Kevin Galligan, Touchlab
20. JetBrains • Coroutines • Ktor • kotlinx.serialization
21. • SQLDelight • okio • okhttp? Touchlab • Stately
23. How to start? • Android Studio • InteliJ IDEA
31. Expect/actual declare expected class/fun/property in common code actually implement in platform-specific code
35. Kotlin/Native • iOS, Linux, Windows, MacOS, WebAssembly... • build full apps or libs • access to native platform APIs • interoperable with C/ObjC(/Swift) • Kotlin can call C/ObjC/Swift and vice-versa • Kotlin can extend ObjC/Swift classes and vice-versa
36. Concurrency is hard • languages/runtimes allow unsafe concurrency • tools - locks & volatile • no warnings • deadlocks • entire burden on devs • no guaranties of safety • bugs leak into production
37. Saner concurrency • new, stricter memory model • ARC with cycle collector • 2 simple rules • Immutable state can be shared among threads • Mutable data belongs to one thread • compiler and runtime check the rules • thread-safe code
38. Saner concurrency ＋GC per thread, no suspends ＋shared reference counter with swift －no global mutable state －new concepts, patterns, practices －coroutines
39. Saner concurrency • Any.freeze() • passing mutable data by detaching • No manual concurrency management • Workers • Atomics - AtomicRef/Int/Long/... • “Stranger threads” (link in resources)
40. Saner concurrency • work in progress • multithreaded coroutines • similar rules for JVM • relaxed memory model
42. Status • beta but relatively stable • low-risk • production • large projects - wait for release • smaller projects - maybe • part of a project - yesterday
44. resources: cutt.ly/kmp-ns email: mmitic89@outlook.com android-serbia slack: @Marko Mitić kotlinlang slack: @Marko Mitic