KMM - Share code between Native Android and Native iOS

This slide is used at Google I/O Extended Vietnam 2021

Transcript

1. Thuy Phan - Android Engineer @LINE @yoyocoder KMM - Share code between Native Android and Native iOS About speaker 1
2. 1. You would like to create a new mobile app for Android and iOS with native look and feel but you don’t want to write the same code twice. 2. You have existing app for Android and iOS, you want to share code between 2 platforms at minimal cost. Problem 2
3. 3 02 What is KMM? 01 Approaches for a mobile app 03 What to share? 04 When to use KMM 05 Conclusion
4. 4 Do you need a mobile app as cheaply as possible? Are you okay with having limited performance if it reduces time-to-market Are you ready to have two dev teams working on separate codebases for each platform Then, you need to choose from these options Are you building an ecommerce app? Are hardware functionalities like camera or GPS a must? Hybrid app Cross-platform app Progressive web app Native app Yes No No No No Yes Yes Yes No Yes
5. 5 02 What is KMM? 01 Approaches for a mobile app 03 What to share? 04 When to use KMM 05 Conclusion
6. What is KMM 6 Kotlin Multiplatforms Mobile Features +
7. 7 Shared Module .jar .framework App App Kotlin/JVM Kotlin/Native
8. Version >= 4.2 Kotlin Multiplatform Mobile plugin Tooling 8 Version >= 11.3
9. KMM Plugin 9
11. Switch IDEs? 11
12. 12 An Kotlin module that builds into the Android application. An Xcode project that builds into the iOS application. The code that works on both platforms, including the expect declarations. Android-specific parts, including actual implementations. iOS-specific parts, including actual implementations.
13. 13 expect class Platform() { val platform: String } actual class Platform actual constructor() { actual val platform: String = "Android ${android.os.Build.VERSION.SDK_INT}" } import platform.UIKit.UIDevice actual class Platform actual constructor() { actual val platform: String = UIDevice.currentDevice.systemName() + " " + UIDevice.currentDevice.systemVersion } shared/androidMain shared/iosMain shared/commonMain
14. 14 02 What is KMM? 01 Approaches for a mobile app 03 What to share? 04 When to use KMM 05 Conclusion
15. Business / Domain (Entities, Use Cases, Interacters) Data / Core (Repositories, HTTP Clients, Cache) Architecture 15 Android iOS UI (Views) Presentation (Presenters, View Models, Controllers)
16. Business logic and core Shared code Android specific APIs CameraX MLKit Room Biometric Play Services Lots of community and libraries 16 View View Native code iOS specific APIs AVFoundation CoreML Local Authentication Accounts Cloudkit Lots of community and libraries
17. Ktor 17 Android Engine Threadpool + HttpURLConnection iOS Engine NSURLSession
18. SQLDelight 18 SQLDelight Android Driver Native Driver
19. 1. You would like to create a new mobile app for Android and iOS with native look and feel but you don’t want to write the same code twice. 2. You have existing app for Android and iOS, you want to share code between 2 platforms at minimal cost. Problem 19
20. 20 Write shared code in KMM Module Take code written in Kotlin for Android Refactor it to be compatible with iOS Implement Native UI on Android/iOS Project New Project Existing Project Connect .framework to iOS project and .jar to Android Project Take a new feature
21. // sample code in shared/commonMain class Greeting { fun greeting(): String { return "Hello, ${Platform().platform}!" } } Unit testing 21
22. 22 expect class Platform() { val platform: String } actual class Platform actual constructor() { actual val platform: String = "Android ${android.os.Build.VERSION.SDK_INT}" } import platform.UIKit.UIDevice actual class Platform actual constructor() { actual val platform: String = UIDevice.currentDevice.systemName() + " " + UIDevice.currentDevice.systemVersion } shared/androidMain shared/iosMain shared/commonMain
23. // in shared/commonTest class CommonGreetingTest { @Test fun testExample() { assertTrue( Greeting().greeting().contains("Hello"), "Check 'Hello' is mentioned" ) } } Unit testing 23
24. // in shared/androidTest class AndroidGreetingTest { @Test fun testExample() { assertTrue( "Check Android is mentioned", Greeting().greeting().contains("Android") ) } } Unit testing 24
25. // in shared/iosTest class IosGreetingTest { @Test fun testExample() { assertTrue( Greeting().greeting().contains("iOS"), "Check iOS is mentioned" ) } } Unit testing 25
26. No different from the usual process described in the Android developer documentation from Google and the iOS developer documentation from Apple. Test & Deploy 26
27. 27 02 What is KMM? 01 Approaches for a mobile app 03 What to share? 04 When to use KMM 05 Conclusion
28. • Incrementally share code between platforms but the native UI. • Your project isn't going to be released very soon. • You don't care about KMM being in alpha status right now. • Your app is complex, tied strongly to multi-thread or has background processing. When to use KMM 28
29. Who uses KMM 29
30. 30 02 What is KMM? 01 Approaches for a mobile app 03 What to share? 04 When to use KMM 05 Conclusion
31. • KMM is still Alpha. • 100% native look and feel on every new OS version. • Single codebase for the business logic. • Get all the cross-platform benefits in your existing project. • Use iOS and Android features without any overhead. • Use Kotlin for cross-platform code. Conclusion 31
32. Thank you! https://kotlinlang.org/docs/m obile/home.html https://kotlinlang.org/lp/mobi le/case-studies/ Resources 32 Thuy Phan - Android Engineer @LINE @yoyocoder