The Hitchhikers Guide Through Kotlin Multiplatform droidcon Online

The Hitchhikers Guide Through Kotlin Multiplatform droidcon Online

Since the early days of mobile that we keep seeing new frameworks being designed to overcome one of the biggest challenges:
- How can I develop for both Android and iOS?

Although it’s initial promises, when we talk about performance, maintainability or even customization we keep discarding these solutions and we always choose native.

Fast forward to the present, and now we have two new languages: Android is Kotlin first and iOS, Swift. And if you put them side by side you can see a lot of similarities between both what will ease switching between one to the other if you have to develop for both platforms.

But what I told that you could just develop in Kotlin and run it seamlessly on all devices? Here comes Kotlin Multiplatform!

D8a3623b157508fecdae1f8e756f362f?s=128

cmota

May 14, 2020
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  1. The Hitchhikers Guide Through Kotlin Multiplatform @cafonsomota droidcon online

  2. hello . @cafonsomota

  3. speakerdeck.com/cmota/ the-hitchhikers-guide-through-kotlin-multiplatform-droidcon-conline @cafonsomota

  4. None
  5. a brief history of time “In the beginning the Universe

    was created. This had made many people angry and has been widely regarded as a bad move.”
  6. Photo by Fabian Grohs on Unsplash

  7. Photo by Fabian Grohs on Unsplash a wild application idea

    appears! develop it for Android and iOS.
  8. -hire a team of specialised developers -define requirements -design mockups

    for both platforms -plan features development -start development/ write unit tests -write t-specs for SQA validation -cross-checking validation between both platforms (or jacks) Steps
  9. ~2xthe team the cost the status meetings required the time

    spent on development the time spent on testing native the time spent on bug fixing
  10. Photo by Fabian Grohs on Unsplash a wild application idea

    appears! develop it for Android and iOS and web.
  11. ~3xthe team the cost the status meetings required the time

    spent on development the time spent on testing the time spent on bug fixing
  12. None
  13. let’s find a solution that works on all platforms.

  14. 2008 2012 2018 2013 2011 2017 2006 2010 2009 2015

    * Kotlin Multiplatform *
  15. - smaller team - typically half of the cost needed

    on native - small learning curve for web developers (advantages) Cross-platform
  16. - chained to the framework implementation of UI - new

    updates from the OS will take time to adopt - performance is not the same - some native code might need to be written - OS/ device features are dependent on the fw support - dart (flutter) is not widely used language (for now) - committed to one framework/ language (disadvantages) Cross-platform
  17. how can we have the best of both worlds?

  18. how can we have the best of both worlds?

  19. kotlin “42.”

  20. None
  21. - developed by JetBrains - open source - concise, safe,

    interoperable, tool-friendly - supported/ used by Google for Android Development - it’s more than “just for Android” Kotlin Server-side Android Kotlin JS Native
  22. Mutability etc. Null safety Default values Type inference String interpolation

    when Collections Easy to learn
  23. Easy to learn - small learning curve involved - easily

    to go from JavaScript/ Swift into Kotlin and back (from a developers’ point of view)
  24. var variable = 42 variable = 1 let value =

    42 var variable = 42 variable = 1 val value = 42 *adapted from http://nilhcem.com/swift-is-like-kotlin/ (variables and constants) Kotlin vs Swift Kotlin Swift
  25. fun greet(name: String, day: String): String { return "Hello $name,

    today is $day." } greet(“World”, “Thursday”) *updated from http://nilhcem.com/swift-is-like-kotlin/ func greet(_ name: String,_ day: String) -> String { return "Hello \(name), today is \(day)." } greet(“World”, “Thursday”) Kotlin Swift (functions) Kotlin vs Swift
  26. class Shape { var numberOfSides = 0 func simpleDescription() ->

    String { return "A shape with \(numberOfSides) sides." } } var shape = Shape() shape.numberOfSides = 7 var shapeDescription = shape.simpleDescription() class Shape { var numberOfSides = 0 fun simpleDescription() = "A shape with $numberOfSides sides." } var shape = Shape() shape.numberOfSides = 7 var shapeDescription = shape.simpleDescription() (variables and constants) Kotlin vs Swift Kotlin Swift
  27. kotlin multiplatform “‘Resistance is useless!’ How can anyone maintain a

    positive mental attitude if you’re saying things like that?”
  28. K otlin multiplatform using kotlin in projects that target more

    than one platform
  29. view view view view model parser network presentation presentation presentation

    presentation network network network parser parser parser model model model presentation presentation presentation desktop web iOS android
  30. business logic business logic business logic model parser network presentation

    model parser network presentation model parser network presentation model parser network presentation business logic view view view view desktop web iOS android
  31. android iOS web desktop model parser network presentation common view

    view view view java/kotlin objective-c/ swift (kotlin) JS supported in jvm
  32. shares application logic doesn’t share the application UI kotlin multiplatform

  33. (advantages) - language features - kotlin first! - low risk

    - you decide what’s worth to share across platforms - interoperability - consistency across platforms - strong community support Kotlin Multiplatform
  34. first reaction

  35. but how can they expect to communicate?

  36. declared at common module expect declared at android module actual

    declared at iOS module declared at …
  37. we want a platform-specific value for name

  38. expect object Platform { val name: String } commonMain src/commonMain/sample/Platform.kt

  39. commonMain src/commonMain/sample/Platform.kt - define actual on android - define actual

    on iOS targets: android and iOS expect object Platform { val name: String }
  40. src/iOSMain/sample/Platform.kt actual object Platform { actual val name: String =

    "Android" } actual object Platform { actual val name: String = "iOS" } src/androidMain/sample/Platform.kt platform-dependent code
  41. IntelliJ will ask you declare the implementations for actual tip:

    just press alt+enter
  42. medium.com/@cafonsomota

  43. show me the code!

  44. demo "For a moment, nothing happened. Then, after a second

    or so, nothing continued to happen.”
  45. github.com/cmota/droidconMAD

  46. - user interface - RecyclerView and more (Android) - UITableViewController

    and more (iOS) - multiple network request - parse response objects - store on local database - notify the UI - that there’s new content available to be draw - reload list project structure
  47. android iOS Room CoreData Retrofit Alamofire GSON/ Moshi JSONSerialization MVP,

    MVVM, MVI MVVM, ELM RxJava RxSwift Tests Tests Activity UIViewController RecyclerView UITableView
  48. Room CoreData Retrofit Alamofire GSON/ Moshi JSONSerialization MVP, MVVM, MVI

    MVVM, ELM RxJava RxSwift Tests Tests Activity UIViewController RecyclerView UITableView android iOS
  49. Room CoreData Retrofit Alamofire GSON/ Moshi JSONSerialization MVP, MVVM, MVI

    MVVM, ELM RxJava RxSwift Tests Tests Activity UIViewController RecyclerView UITableView android iOS Activity UIViewController RecyclerView UITableView unnecessary duplication
  50. SQLDelight ktor kotlinx.serialization MVP kotlinx.coroutines kotlin.test android iOS Activity UIViewController

    RecyclerView UITableView
  51. multiplatform httpClient ktor SQLDelight android kotlinx.serialization SQLDriver dispatcher view presenter

    presenter model GetSchedule GetSpeakers
  52. multiplatform httpClient ktor SQLDelight iOS model kotlinx.serialization GetSchedule GetSpeakers SQLDriver

    dispatcher view presenter presenter
  53. multiplatform network database android parser presenter presenter view platform domain

    specific model
  54. class SessionizeAPI(engine: HttpClientEngine) { private val client = HttpClient(engine) {

    install(JsonFeature) { serializer = KotlinxSerializer() } } suspend fun fetchSpeakers(): List<SpeakerEntity> { val response = client.get<HttpResponse>{ url ("$URL")} val json = response.readText() return Json.parse(SpeakerEntity.serializer().list, json) } } network src/commonMain/data/SessionizeAPI.kt ktor multiplatform network database android parser view platform specific presenter presenter domain model common (shared) code
  55. kotlinx.serialization network src/commonMain/data/SessionizeAPI.kt class SessionizeAPI(engine: HttpClientEngine) { private val client

    = HttpClient(engine) { install(JsonFeature) { serializer = KotlinxSerializer() } } suspend fun fetchSpeakers(): List<SpeakerEntity> { val response = client.get<HttpResponse>{ url ("$URL")} val json = response.readText() return Json.parse(SpeakerEntity.serializer().list, json) } } multiplatform network database android parser view platform specific presenter presenter domain model
  56. json response [{ "id": "2bc1e95f-1243-4ad0-8a11-75541fee10e0", "firstName": "Carlos", "lastName": "Mota", "fullName":

    "Carlos Mota", "bio": "… GDG Coimbra organizer and Kotlin evangelist, he also has a huge passion for travel, photography, space and the occasional run.", "tagLine": "Lead Software Engineer at WIT Software", "profilePicture": “https://sessionize.com/imag...7ef8707ae.jpg”, "sessions": [{ "id": 131513, "name": "The Hitchhikers Guide Through Kotlin Multiplatform" }], … },… https://sessionize.com/api/v2/3hvwlgcc/view/speakers
  57. json response [{ "id": "2bc1e95f-1243-4ad0-8a11-75541fee10e0", "firstName": "Carlos", "lastName": "Mota", "fullName":

    "Carlos Mota", "bio": "… GDG Coimbra organizer and Kotlin evangelist, he also has a huge passion for travel, photography, space and the occasional run.", "tagLine": "Lead Software Engineer at WIT Software", "profilePicture": “https://sessionize.com/imag...7ef8707ae.jpg”, "sessions": [{ "id": 131513, "name": "The Hitchhikers Guide Through Kotlin Multiplatform" }], … },… https://sessionize.com/api/v2/3hvwlgcc/view/speakers
  58. kotlinx.serialization src/commonMain/data/entities/SpeakerEntity.kt multiplatform network database android parser view platform specific

    presenter presenter domain model parser @Serializable data class SpeakerEntity ( val id: String, val firstName: String, val lastName: String, val fullName: String, val bio: String, val tagLine: String, val profilePicture: String, val sessions: List<SessionShortEntity>, val isTopSpeaker: Boolean, val links: List<String>, val questionAnswers: List<String>, val categories: List<String>)
  59. database CREATE TABLE SpeakerModel ( id TEXT NOT NULL PRIMARY

    KEY, speaker TEXT as Speaker NOT NULL ); insertOrReplaceSpeaker: INSERT OR REPLACE INTO SpeakerModel(id, speaker) VALUES (?, ?); selectAllSpeakers: SELECT * FROM SpeakerModel; SQLDelight src/commonMain/sqldelight/data/model/SpeakerModel.sq multiplatform network database android parser view platform specific presenter presenter domain model
  60. database SQLite SQLDelight multiplatform network database android parser view platform

    specific presenter presenter domain model
  61. database SQLite Compiler Generated code SQLDelight multiplatform network database android

    parser view platform specific presenter presenter domain model
  62. database Generated code SQLDelight multiplatform network database android parser view

    platform specific presenter presenter domain model
  63. app/build/sqldelight/ScheduleDb/data/app/ScheduleDbImpl.kt database class SpeakerModelQueriesImpl(private val db: ScheduleDbImpl, private val driver:

    SqlDriver) : TransacterImpl(driver), SpeakerModelQueries { … override fun insertOrReplaceSpeaker(id: String, speaker: Speaker) { driver.execute(2113668020, """INSERT OR REPLACE INTO SpeakerModel(id, speaker) |VALUES (?1, ?2)""", 2) { bindString(1, id) bindString(2, db.SpeakerModelAdapter.speakerAdapter.encode(speaker)) } notifyQueries(2113668020, {db.speakerModelQueries.selectAllSpeakers}) } } generated class SQLDelight multiplatform network database android parser view platform specific presenter presenter domain model
  64. model class SpeakerDao(database: ScheduleDb) { private val db = database.speakerModelQueries

    internal fun insertOrReplace(speaker: Speaker) { db.insertOrReplaceSpeaker( id = speaker.id, speaker = speaker) } internal fun getAllSpeakers(): List<Speaker> { val data = db.selectAllSpeakers().executeAsList() … src/commonMain/domain/dao/SpeakerDao.kt multiplatform network database android parser view platform specific presenter presenter domain model
  65. model @Serializable data class Speaker ( val id: String, val

    fullName: String, val bio: String, val tagLine: String, val profilePicture: String, val sessions: List<Info>, val categories: List<String>) fun SpeakerEntity.toSpeaker() = Speaker( id = id, fullName = fullName, bio = bio, …) src/commonMain/domain/model/Speaker.kt multiplatform network database android parser view platform specific presenter presenter domain model
  66. domain class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) { suspend

    operator fun invoke(onSuccess: (List<Speaker>) -> Unit, onFailure: (Exception) -> Unit) { try { val result = api.fetchSpeakers() val speakers = Speaker.toSpeaker(result) dao.insertOrReplace(speakers) coroutineScope { onSuccess(speakers) } } catch (e: Exception) { onFailure(e) } src/commonMain/domain/GetSpeakers.kt multiplatform network database android parser view platform specific presenter presenter domain model
  67. domain class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) { suspend

    operator fun invoke(onSuccess: (List<Speaker>) -> Unit, onFailure: (Exception) -> Unit) { try { val result = api.fetchSpeakers() val speakers = Speaker.toSpeaker(result) dao.insertOrReplace(speakers) coroutineScope { onSuccess(speakers) } } catch (e: Exception) { onFailure(e) } src/commonMain/domain/GetSpeakers.kt multiplatform network database android parser view platform specific presenter presenter domain model
  68. domain class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) { suspend

    operator fun invoke(onSuccess: (List<Speaker>) -> Unit, onFailure: (Exception) -> Unit) { try { val result = api.fetchSpeakers() val speakers = Speaker.toSpeaker(result) dao.insertOrReplace(speakers) coroutineScope { onSuccess(speakers) } } catch (e: Exception) { onFailure(e) } src/commonMain/domain/GetSpeakers.kt multiplatform network database android parser view platform specific presenter presenter domain model
  69. domain class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) { suspend

    operator fun invoke(onSuccess: (List<Speaker>) -> Unit, onFailure: (Exception) -> Unit) { try { val result = api.fetchSpeakers() val speakers = Speaker.toSpeaker(result) dao.insertOrReplace(speakers) coroutineScope { onSuccess(speakers) } } catch (e: Exception) { onFailure(e) } src/commonMain/domain/GetSpeakers.kt multiplatform network database android parser view platform specific presenter presenter domain model
  70. class SpeakersListPresenter(val speakers: GetSpeakers, val coroutineContext: CoroutineContext) { lateinit var

    view: ISpeakersData fun attachView(currView: ISpeakersData) { view = currView fetchSpeakersList() } … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/presentation/SpeakersListPresenter.kt
  71. class SpeakersListPresenter(val speakers: GetSpeakers, val coroutineContext: CoroutineContext) { lateinit var

    view: ISpeakersData fun attachView(currView: ISpeakersData) { view = currView fetchSpeakersList() } … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/presentation/SpeakersListPresenter.kt onCreate()/ viewDidLoad()
  72. class SpeakersListPresenter(val speakers: GetSpeakers, val coroutineContext: CoroutineContext) { lateinit var

    view: ISpeakersData fun attachView(currView: ISpeakersData) { view = currView fetchSpeakersList() } … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/presentation/SpeakersListPresenter.kt
  73. presenter multiplatform network database android parser view platform specific presenter

    presenter domain model src/commonMain/presentation/cb/ISpeakersData.kt interface ISpeakersData { fun onSpeakersDataFetched(speakers: List<Speaker>) fun onSpeakersDataFailed(e: Exception) }
  74. class SpeakersListPresenter(val speakers: GetSpeakers, val coroutineContext: CoroutineContext) { lateinit var

    view: ISpeakersData fun attachView(currView: ISpeakersData) { view = currView fetchSpeakersList() } private fun fetchSpeakersList() { PresenterCoroutineScope(coroutineContext).launch { speakers( onSuccess = { view?.onSpeakersDataFetched(it) }, onFailure = { view?.onSpeakersDataFailed(it) }) … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/presentation/SpeakersListPresenter.kt
  75. class SpeakersListPresenter(val speakers: GetSpeakers, val coroutineContext: CoroutineContext) { lateinit var

    view: ISpeakersData fun attachView(currView: ISpeakersData) { view = currView fetchSpeakersList() } private fun fetchSpeakersList() { PresenterCoroutineScope(coroutineContext).launch { speakers( onSuccess = { view?.onSpeakersDataFetched(it) }, onFailure = { view?.onSpeakersDataFailed(it) }) … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/presentation/SpeakersListPresenter.kt
  76. object ServiceLocator { private val sessionizeAPI by lazy { SessionizeAPI(PlatformServiceLocator.httpClientEngine)

    } private val speakerDao by lazy { SpeakerDao(PlatformServiceLocator.databaseEngine) } private val getSpeakers: GetSpeakers get() = GetSpeakers(sessionizeAPI, speakerDao) val getSpeakersPresenter: SpeakersListPresenter get() = SpeakersPresenter(getSpeakers) … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/ServiceLocator.kt
  77. object ServiceLocator { private val sessionizeAPI by lazy { SessionizeAPI(PlatformServiceLocator.httpClientEngine)

    } private val speakerDao by lazy { SpeakerDao(PlatformServiceLocator.databaseEngine) } private val getSpeakers: GetSpeakers get() = GetSpeakers(sessionizeAPI, speakerDao) val getSpeakersPresenter: SpeakersListPresenter get() = SpeakersPresenter(getSpeakers) … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/ServiceLocator.kt called by the UI
  78. object ServiceLocator { private val sessionizeAPI by lazy { SessionizeAPI(PlatformServiceLocator.httpClientEngine)

    } private val speakerDao by lazy { SpeakerDao(PlatformServiceLocator.databaseEngine) } private val getSpeakers: GetSpeakers get() = GetSpeakers(sessionizeAPI, speakerDao) val getSpeakersPresenter: SpeakersListPresenter get() = SpeakersPresenter(getSpeakers) … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/ServiceLocator.kt
  79. object ServiceLocator { private val sessionizeAPI by lazy { SessionizeAPI(PlatformServiceLocator.httpClientEngine)

    } private val speakerDao by lazy { SpeakerDao(PlatformServiceLocator.databaseEngine) } private val getSpeakers: GetSpeakers get() = GetSpeakers(sessionizeAPI, speakerDao) val getSpeakersPresenter: SpeakersListPresenter get() = SpeakersPresenter(getSpeakers) … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/ServiceLocator.kt
  80. object ServiceLocator { private val sessionizeAPI by lazy { SessionizeAPI(PlatformServiceLocator.httpClientEngine)

    } private val speakerDao by lazy { SpeakerDao(PlatformServiceLocator.databaseEngine) } private val getSpeakers: GetSpeakers get() = GetSpeakers(sessionizeAPI, speakerDao) val getSpeakersPresenter: SpeakersListPresenter get() = SpeakersPresenter(getSpeakers) … presenter multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/ServiceLocator.kt
  81. None
  82. platform specific expect object PlatformServiceLocator { val httpClientEngine: HttpClientEngine val

    databaseEngine: ScheduleDb } multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/PlatformServiceLocator.kt
  83. platform specific expect object PlatformServiceLocator { val httpClientEngine: HttpClientEngine val

    databaseEngine: ScheduleDb } multiplatform network database android parser view platform specific presenter presenter domain model src/commonMain/PlatformServiceLocator.kt
  84. platform specific expect object PlatformServiceLocator { val httpClientEngine: HttpClientEngine val

    databaseEngine: ScheduleDb } commonMain
  85. platform specific expect object PlatformServiceLocator { val httpClientEngine: HttpClientEngine val

    databaseEngine: ScheduleDb } commonMain actual object PlatformServiceLocator { actual val httpClientEngine: HttpClientEngine by lazy { OkHttp.create() } actual val databaseEngine: SqlDriver by lazy { AndroidSqliteDriver(ScheduleDb.Schema, ctx, “app.db") … androidMain
  86. platform specific expect object PlatformServiceLocator { val httpClientEngine: HttpClientEngine val

    databaseEngine: ScheduleDb } commonMain actual object PlatformServiceLocator { actual val httpClientEngine: HttpClientEngine by lazy { OkHttp.create() } actual val databaseEngine: SqlDriver by lazy { AndroidSqliteDriver(ScheduleDb.Schema, ctx, “app.db") … androidMain actual object PlatformServiceLocator { actual val httpClientEngine: HttpClientEngine by lazy { Ios.create() } actual val databaseEngine: SqlDriver by lazy { NativeSqliteDriver(ScheduleDb.Schema, “app.db") … iOSMain
  87. platform specific expect object PlatformServiceLocator { val httpClientEngine: HttpClientEngine val

    databaseEngine: ScheduleDb } commonMain actual object PlatformServiceLocator { actual val httpClientEngine: HttpClientEngine by lazy { OkHttp.create() } actual val databaseEngine: SqlDriver by lazy { AndroidSqliteDriver(ScheduleDb.Schema, ctx, “app.db") … androidMain actual object PlatformServiceLocator { actual val httpClientEngine: HttpClientEngine by lazy { Ios.create() } actual val databaseEngine: SqlDriver by lazy { NativeSqliteDriver(ScheduleDb.Schema, “app.db") … iOSMain
  88. platform specific actual object PlatformServiceLocator { actual val httpClientEngine: HttpClientEngine

    by lazy { OkHttp.create() } actual val databaseEngine: SqlDriver by lazy { AndroidSqliteDriver(ScheduleDb.Schema, ctx, “app.db") … androidMain actual object PlatformServiceLocator { actual val httpClientEngine: HttpClientEngine by lazy { Ios.create() } actual val databaseEngine: SqlDriver by lazy { NativeSqliteDriver(ScheduleDb.Schema, “app.db") … iOSMain multiplatform network database android parser view platform specific presenter presenter domain model
  89. src/commonAndroid/presenter/activities/MainActivity.kt android class MainActivity : AppCompatActivity(), ISpeakersData { val presenter

    by lazy { ServiceLocator.getSpeakersPresenter } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) presenter.attachView(this) } override fun onSpeakersDataFetched(list: List<Speaker>){ setup(list) … multiplatform network database android parser view platform specific presenter presenter domain model
  90. src/commonAndroid/presenter/activities/MainActivity.kt android class MainActivity : AppCompatActivity(), ISpeakersData { val presenter

    by lazy { ServiceLocator.getSpeakersPresenter } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) presenter.attachView(this) } override fun onSpeakersDataFetched(list: List<Speaker>){ setup(list) … multiplatform network database android parser view platform specific presenter presenter domain model
  91. src/commonAndroid/presenter/adapters/SpeakersListAdapter.kt android multiplatform network database android parser view platform specific

    presenter presenter domain model override fun onBindViewHolder(viewHolder: SpeakerViewHolder, position: Int) { val speaker = speakers[position] Glide.with(viewHolder.speakerPhoto) .load(speaker.profilePicture) .apply(RequestOptions.circleCropTransform()) .into(viewHolder.speakerPhoto) viewHolder.speakerName.text = speaker.fullName viewHolder.talkTitle.text = speaker.talkTitle viewHolder.container.setOnClickListener { action.onUserClickAction(speaker, it) } }
  92. src/commonAndroid/presenter/adapters/SpeakersListAdapter.kt android override fun onBindViewHolder(viewHolder: SpeakerViewHolder, position: Int) { val

    speaker = speakers[position] Glide.with(viewHolder.speakerPhoto) .load(speaker.profilePicture) .apply(RequestOptions.circleCropTransform()) .into(viewHolder.speakerPhoto) viewHolder.speakerName.text = speaker.fullName viewHolder.talkTitle.text = speaker.talkTitle viewHolder.container.setOnClickListener { action.onUserClickAction(speaker, it) } } you can keep using your android libraries multiplatform network database android parser view platform specific presenter presenter domain model
  93. iosApp/iosApp/SpeakerTableViewController.swift iOS multiplatform network database iOS parser view platform specific

    presenter presenter domain model class SpeakerTableViewController: UITableViewController, ISpeakersData lazy var presenter = ServiceLocator.init().getSpeakerPresenter override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(animated) presenter.attachView(view: self) } func onSpeakersDataFetched(speakers: [Speaker]) { setup(speakers) …
  94. iosApp/iosApp/SpeakerTableViewController.swift iOS multiplatform network database iOS parser view platform specific

    presenter presenter domain model class SpeakerTableViewController: UITableViewController, ISpeakersData { lazy var presenter = ServiceLocator.init().getSpeakersPresenter override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(animated) presenter.attachView(view: self) } func onSpeakersDataFetched(speakers: [Speaker]) { setup(speakers) …
  95. iosApp/iosApp/SpeakerTableViewController.swift iOS multiplatform network database iOS parser view platform specific

    presenter presenter domain model override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cellIdentifier = "SpeakerTableViewCell" let cell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier, for: indexPath) as SpeakerTableViewCell let speaker = speakers[indexPath.row] cell.talkName.text = speaker.talkTitle cell.speakerName.text = speaker.fullName cell.speakerImage.image = speaker.profilePicture return cell }
  96. how much sharing? what makes sense for your app kotlin

    multiplatform
  97. conclusions don’t forget to bring your own towel.

  98. - it’s in experimental state - although we keep seeing

    new projects in production - Space was announced during Kotlin Conf 19 (web, desktop and mobile) (apps in production) Kotlin Multiplatform Space Adapted from: KotlinConf 2019: Opening Keynote by Andrey Breslav Full KMP Cash App Shares: business logic Yandex Maps Shares: business logic, wrappers for C++ libraries PlanGrid Planboard Workspace Shares: business logic, sync logic, mgmnt offline data Shares: business logic, networking, offline caching lyrs Shares: business logic
  99. - start small, don’t try to reach 100% of shared

    logic - perhaps by writing common tests to gain familiarity - one module at a time (network, database, image processing, etc.) - you can spend some time resolving compilation issues - specially if you try to target all platforms (how to start?) Kotlin Multiplatform - it’s in experimental state - experimental means that one library update can break your builds - lookout for plugins/ libraries updates
  100. - evangelize the iOS team - select one module where

    something is more complex on iOS than on Android - KMP is not intended to share the UI - iOS developers can focus on Swift and frontend features - Cross platform solutions like Flutter or React Native they need to use Dart or JS - not possible to debug kotlin from Xcode - plugin for Xcode from TouchLab/ support mentioned on Kotlin Conf 19 (how to start?) Kotlin Multiplatform
  101. - strong community - a lot of people are using

    kotlin nowadays - Google and JetBrains are pushing Kotlin in - you can ask questions directly on https://kotlinlang.slack.com - 2x faster to develop your features business logic - 2x faster writing unit tests - one tech stack - consistency across platforms (conclusions) Kotlin Multiplatform
  102. - Ktor (networking) - Kotlinx.Coroutines - Kotlinx.Serialization - SqlDelight (database)

    - Multiplatform Settings (hello Russell ) - Stately (state management) (libraries) more information
  103. - .../JetBrains/kotlinconf-app - .../touchlab/DroidconKotlin - …/touchlab/KaMPKit - .../wojtek-kalicinski/sudoku-android - .../joreilly/PeopleInSpace

    - .../jonnyzzz/kotlin-game-of-life - .../MarcinMoskala/WorkoutMPP (cool projects to follow at GitHub) more information
  104. - Kotlin Slack - Kotlin Official - Kotlin by: https://jakewharton.com/presentations/

    https://touchlab.co/kamp-kit-touchlab/ - Kotlin Conf 2019 videos https://www.youtube.com/watch?v=0xKTM0A8gdI (useful links) more information
  105. @cafonsomota so long and thanks for all the fish medium.com/@cafonsomota

    github.com/cmota/droidconMAD