Developing Multiplatform Projects in Kotlin 1.2

As presented on JEEConf 2018

Transcript

1. @intelliyole Dmitry Jemerov Developing Multiplatform Projects in Kotlin 1.2
2. Server Android Browser Kotlin/JVM Kotlin/JVM Kotlin/Native Kotlin/JS iOS Kotlin/Anywhere
3. Shared business logic, platform-specific UI • Share • Data model • Validation rules • Network client code • HTML generation • Platform-specific • UI • Usages of unique APIs on each platform
4. Common libraries • Standard library • Collections and sequences • Functional operations on collections (filter, map etc.) • Higher-order utility functions (with, apply etc.) • Exceptions • Testing • Higher-level infrastructure libraries
5. Multiplatform
 projects
6. Platform module Platform module Common module
7. Common *.kt Kotlin/JVM *.kt, *.java *.class
 *.jar, *.apk Kotlin/JS *.kt, *.js *.js Kotlin/Native *.kt native binary
8. package kotlin.date expect class Date { … fun getFullYear(): Int … } Common JS package kotlin.date actual external class Date { actual fun getFullYear(): Int } package kotlin.date actual class Date { private val calendar: Calendar … actual fun getFullYear() = calendar[YEAR] … } JVM
9. fun isSameDay(from: Date, to: Date) = from.getFullYear() !== to.getFullYear() !&& !!... package kotlin.date expect class Date { … fun getFullYear(): Int … } Common
10. Why not interfaces? Common expect class Date { constructor(value: Number) } expect fun parseDate(dateString: String): Date expect fun Date.toReadableDateString(): String
11. Reusing existing implementations package kotlin.test actual typealias Test = org.junit.Test JVM package kotlin.test expect annotation class Test() Common
12. Building a common module apply plugin: 'kotlin-platform-common' dependencies { compile "org.jetbrains.kotlin:kotlin-stdlib-common:$version" } Common
13. apply plugin: 'kotlin-platform-jvm' dependencies { compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$version" expectedBy project(":konf-common") } JVM Building a platform module
14. Common *.kt Kotlin/JS *.kt, *.js *.js Kotlin/JVM *.kt, *.java *.jar Common Libraries *.kotlin_metadata Kotlin/Native *.kt *.klib
15. Multiplatform
 libraries
16. kotlin.test import kotlin.test.Test import kotlin.test.assertEquals class DateTest { @Test fun testParse() { val date = parseDate("2017-11-02") assertEquals(2017, date.getFullYear()) } }
17. kotlinx.html div { a("http:!//kotlinlang.org") { target = ATarget.blank +"Main site" } }
18. kotlinx.html div { aNewWindow("http:!//kotlinlang.org") { +"Main site" } }
19. kotlinx.serialization • @Serializable • Compiler plugin to generate serialization calls (no reflection) • JSON and ProtoBuf support
20. kotlinx.coroutines fun main(args: Array<String>) = runBlocking<Unit> { val time = measureTimeMillis { val one = async { doSomethingUsefulOne() } val two = async { doSomethingUsefulTwo() } println("The answer is ${one.await() + two.await()}") } println("Completed in $time ms") }
21. Future plans • I/O • Networking (TCP, HTTP etc.) • Dates • and more
22. Sample projects • https://github.com/jetbrains/kotlinconf-app • https://github.com/yole/kxhtml-isomorphic • https://github.com/jetbrains/kotlin-native/samples/calculator
23. DEMO
24. Kotlin/Native
25. Kotlin/Native for iOS LLVM-based toolchain Native Binary LLVM
26. cinterop • Clang-based tool to generate Kotlin metadata from C header files • Supports all C types: strings, pointers, structs, callbacks • Supports Objective-C types
27. iOS libraries
28. iOS libraries fun showGameCenter() { val gkViewController = GKGameCenterViewController().apply { gameCenterDelegate = this@ViewController viewState = GKGameCenterViewControllerStateLeaderboards leaderboardTimeScope = GKLeaderboardTimeScopeToday leaderboardCategory = "main" } this.presentViewController(gkViewController, 
 animated = true, completion = null) }
29. Kotlin/Native iOS Interop • Compiling Kotlin/Native module to iOS framework • Autogeneration of .h files • Easy conversions between Kotlin and ObjC types (NSString, NSArray, NSDictionary)
30. Kotlin/Native Memory management • Reference counting + cycle collector • No shared mutable state between threads • Support of frozen objects • Still under design; final version might be different
31. Kotlin/Native Target Platforms • Windows, Linux, macOS • iOS, Android • WebAssembly • Embedded (STM32 board currently supported)
32. Tooling • Plugin for CLion and AppCode • All features of regular Kotlin plugin • Debugger • Test runner
33. Tooling
34. Tooling
35. Sample projects • https://github.com/jetbrains/kotlinconf-spinner • https://github.com/JetBrains/kotlin-native/tree/master/samples
36. DEMO
37. Kotlin/JS
38. *.d.ts ts2kt kotlinc *.kt *.js Compiling a Kotlin/JS project webpack bundle.js *.js
39. External declarations external abstract class Window { val location: Location fun alert(message: String) !// … } external val window: Window
40. dynamic type val response: dynamic = loadJson("example.com/api") val text = response.messages[0].text
41. React support • Official bindings for react • https://github.com/jetbrains/kotlin-wrappers • CLI tool to create React application • npm install -g create-react-kotlin-app • create-react-kotlin-app my-app
42. kotlin-frontend-plugin • Download JS dependencies from npm • Create bundle using webpack • Run tests using Karma • Hot reload of changes
43. Summary • Kotlin's goal is to allow you to write all parts of your app in the same language • Full interoperability on every supported platform • Shared business logic, platform-specific UI • JVM/JS code reuse available today, native coming soon
44. To learn more • http://kotlinlang.org/ • http://blog.jetbrains.com/kotlin • http://slack.kotlinlang.org/
45. @intelliyole Dmitry Jemerov Thank you!