What’s New in Kotlin Multiplatform?

What do I need to do to set up a Multiplatform Kotlin app? The answer looks different today than it did two years ago. Many tutorials and samples you find online are out of date, and there’s lots of conflicting advice about how to configure things. With Kotlin 1.4 recently released, it’s a great time to take stock of where things are, and what things you might want to change compared to a year or two ago.

Drawing on questions I’ve seen from the community and in consulting work, as well as my experience building one of the early Kotlin Multiplatform libraries, I’ll catalogue some useful tips and tricks for Multiplatform projects. We’ll talk about common pitfalls and useful tools and examples. Whether you’re maintaining a project that’s starting to show its age, or you’re just getting started, we’ll get you up-to-speed on the latest advice.

Transcript

1. @RussHWolf ( or ) What's New in Kotlin Multiplatform Droidcon Americas 2020 Russell Wolf
3. Kotlin is a language for... • Android • JVM (Server, Desktop) • JS (Browser, Node) • Native (LLVM, C interop) • iOS (Objective-C Interop)
4. Kotlin Multiplatform • Common code compiles to multiple targets • Platform-specific code can interop with that platform • Flexible - share only what makes sense to your use-case
5. Kevin Galligan "Shared UI is a history of pain and failure. Shared logic is the history of computers."
6. Mobile is the killer app for Kotlin Multiplatform
7. https://kotlinlang.org/lp/mobile/
8. MPP KMP
 KMM
9. Shared Code
10. Shared Code Android Common iOS
11. Shared Code Android Common iOS
12. Shared Code Android Common iOS
13. Shared Code Android Common iOS
14. Shared Code Android Common iOS
15. Shared Code Android Common iOS
16. Shared Code Android Common iOS
17. Architecture
18. Common iOS Framework Android AAR Architecture
19. Common iOS Framework Android AAR Android App iOS App Architecture
20. ... ... Common iOS Framework Android AAR Android App iOS App Architecture
21. Common iOS Framework Android AAR ... ... Android App iOS App ... Architecture
22. Multiplatform Code
23. Common Code // Common
 class Thing(val data: List<String>) { fun doSomething() { data.forEach { println(it) } } }
24. Platform-Specific Code // Common
 expect val platform: String
 // Android
 actual val platform = "Android" 
 // iOS
 actual val platform = "iOS"
25. Platform-Specific Code // Common
 interface Logger { fun log(message: String) }
 // Android
 class AndroidLogger : Logger { ... }
 // iOS - Kotlin
 class IosLogger { ... }
 // iOS - Swift class SwiftLogger : Logger { ... } // Common
 class TestLogger : Logger
26. So What's New?
27. Docs!
28. https://kotlinlang.org/lp/mobile/
29. https://kotlinlang.org/docs/mobile
30. https://kotlinlang.org/docs/reference/mpp-intro.html
31. Tooling
32. KMM Android Studio Plugin
33. Xcode Kotlin Plugin https://github.com/touchlab/xcode-kotlin
34. IDEA Project Wizard
35. Heirarchical Project Structure and Gradle Metadata
36. Heirarchical Project Structure kotlin.mpp.enableGranularSourceSetsMetadata=true
 kotlin.native.enableDependencyPropagation=false
37. Threading
38. Kotlin/Native Threading
39. Libraries
40. kotlinx-coroutines https://github.com/Kotlin/kotlinx.coroutines • Suspend functions and Flows • Separate single-threaded and multithreaded versions • 1.3.9 vs 1.3.9-native-mt
41. ktor https://github.com/ktorio/ktor • Http client • Uses native-mt coroutines version
42. kotlinx-serialization https://github.com/Kotlin/kotlinx.serialization • Multi-format serialization • First stable release! • API changes • New docs
43. kotlinx-datetime https://github.com/Kotlin/kotlinx-datetime • New! • Small API surface • Report issues and use-cases
44. Jetpack Compose?
45. Community libs • SqlDelight • Multiplatform Settings • Stately • Koin, Kodein • More at: • https://github.com/AAkira/Kotlin-Multiplatform-Libraries • https://kotlinlang.org/lp/mobile/ecosystem/
46. Samples
47. KaMPKit https://github.com/touchlab/KaMPKit
48. https://github.com/joreilly/PeopleInSpace https://github.com/joreilly/BikeShare
49. https://github.com/russhwolf/multiplatform-hello
50. ... and more
51. Resources • KMM Portal: https://kotlinlang.org/lp/mobile/ • KMM Docs: https://kotlinlang.org/docs/mobile/samples.html • Multiplatform Docs: https://kotlinlang.org/docs/reference/mpp-intro.html • Codelabs: https://play.kotlinlang.org/hands-on/overview • Roadmap: https://kotlinlang.org/roadmap.html • KaMPKit: https://github.com/touchlab/KaMPKit
52. @RussHWolf ( or ) Questions? Russell Wolf