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Android Makers: Virtual Edition
The Hitchhikers Guide Through
Kotlin Multiplatform
@cafonsomota
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hello .
@cafonsomota
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Questions?
bit.ly/kmp-androidmakers
@cafonsomota
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speakerdeck.com/cmota/
the-hitchhikers-guide-through-kotlin-multiplatform-androidmakers
@cafonsomota
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No content
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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.”
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android iOS
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Photo by Fabian Grohs on Unsplash
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Photo by Fabian Grohs on Unsplash
a wild application idea
appears!
develop it for Android and iOS.
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-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
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~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
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Photo by Fabian Grohs on Unsplash
a wild application idea
appears!
develop it for Android and iOS and web.
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~3xthe team
the cost
the status meetings required
the time spent on development
the time spent on testing
the time spent on bug fixing
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No content
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let’s find a solution
that works on all
platforms.
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2008 2012 2018
2013
2011 2017
2006 2010
2009 2015
* Kotlin Multiplatform
*
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- smaller team
- typically half of the cost needed on native
- small learning curve for web developers
(advantages)
Cross-platform
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- 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
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how can we have
the best of both
worlds?
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how can we have
the best of both
worlds?
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kotlin
“42.”
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- 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
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Mutability
etc.
Null safety
Default
values
Type
inference
String
interpolation
when
Collections
Easy to learn
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Easy to learn
- small learning curve involved
- easily to go from JavaScript/ Swift into Kotlin and back
(from a developers’ point of view)
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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
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fun greet(name: String, day: String): String {
return "Hello $name, today is $day."
}
greet(“Paris”, “Monday”)
*updated from http://nilhcem.com/swift-is-like-kotlin/
func greet(_ name: String,_ day: String) -> String {
return "Hello \(name), today is \(day)."
}
greet(“Paris”, “Monday”)
Kotlin
Swift
(functions)
Kotlin vs Swift
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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
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kotlin multiplatform
“‘Resistance is useless!’ How can anyone maintain a positive mental
attitude if you’re saying things like that?”
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K
otlin multiplatform
using kotlin in projects
that target more than
one platform
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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
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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
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android iOS web desktop
model
parser
network
presentation
common
view view view view
java/kotlin objective-c/ swift (kotlin) JS supported in jvm
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shares application logic
doesn’t share the application UI
kotlin
multiplatform
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(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
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first reaction
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but how can they expect to communicate?
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declared at common module
expect
declared at android module
actual
declared at iOS module
declared at …
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we want a platform-specific value for name
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expect object Platform {
val name: String
}
commonMain
src/commonMain/sample/Platform.kt
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commonMain
src/commonMain/sample/Platform.kt
- define actual on android
- define actual on iOS
targets: android and iOS
expect object Platform {
val name: String
}
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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
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IntelliJ will ask you declare the implementations for actual
tip: just press alt+enter
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*.kt
common
expect
JVM
actual
*.kt, *.java, *.jar
Native
actual
*.kt, *C, Swift, Framework
JS
actual
*.kt, *.js, NPM
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medium.com/@cafonsomota
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show me the code!
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demo
"For a moment, nothing happened. Then, after a second or so, nothing
continued to happen.”
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(optional)
(or AppCode)
IDE’s required
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src/
commonMain/
commonTest/
app/
project structure
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src/
commonMain/
commonTest/
app/
project structure
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androidMain
androidTest
project structure
src/
commonMain/
commonTest/
app/
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project structure
src/
commonMain/
commonTest/
app/
androidMain
androidTest
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project structure
src/
commonMain/
commonTest/
app/
androidMain
androidTest
iosMain/
iosTest/
jsMain/
jsTest/
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github.com/cmota/androidmakers
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- 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
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android iOS
Room CoreData
Retrofit Alamofire
GSON/ Moshi JSONSerialization
MVP, MVVM, MVI MVVM, ELM
RxJava RxSwift
Tests Tests
Activity UIViewController
RecyclerView UITableView
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Room CoreData
Retrofit Alamofire
GSON/ Moshi JSONSerialization
MVP, MVVM, MVI MVVM, ELM
RxJava RxSwift
Tests Tests
Activity UIViewController
RecyclerView UITableView
android iOS
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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
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SQLDelight
ktor
kotlinx.serialization
MVP
kotlinx.coroutines
kotlin.test
android iOS
Activity UIViewController
RecyclerView UITableView
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multiplatform
httpClient
ktor
SQLDelight
android
kotlinx.serialization
SQLDriver dispatcher
view
presenter
presenter
model
GetSchedule GetSpeakers
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multiplatform
httpClient
ktor
SQLDelight
iOS
model
kotlinx.serialization
GetSchedule GetSpeakers
SQLDriver dispatcher
view
presenter
presenter
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multiplatform
network
database
android
parser
presenter
presenter
view
platform
domain
specific
model
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class SessionizeAPI(engine: HttpClientEngine) {
private val client = HttpClient(engine) {
install(JsonFeature) {
serializer = KotlinxSerializer()
}
}
suspend fun fetchSpeakers(): List {
val response = client.get{ 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
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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 {
val response = client.get{ 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
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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
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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
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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,
val isTopSpeaker: Boolean,
val links: List,
val questionAnswers: List,
val categories: List)
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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
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database
SQLite
SQLDelight
multiplatform
network
database
android
parser
view
platform
specific
presenter
presenter
domain
model
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database
SQLite Compiler Generated code
SQLDelight
multiplatform
network
database
android
parser
view
platform
specific
presenter
presenter
domain
model
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database
Generated code
SQLDelight
multiplatform
network
database
android
parser
view
platform
specific
presenter
presenter
domain
model
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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
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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 {
val data = db.selectAllSpeakers().executeAsList()
…
src/commonMain/domain/dao/SpeakerDao.kt multiplatform
network
database
android
parser
view
platform
specific
presenter
presenter
domain
model
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model
@Serializable
data class Speaker (
val id: String,
val fullName: String,
val bio: String,
val tagLine: String,
val profilePicture: String,
val sessions: List,
val categories: List)
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
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domain
class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) {
suspend operator fun invoke(onSuccess: (List) -> 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
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domain
class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) {
suspend operator fun invoke(onSuccess: (List) -> 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
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domain
class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) {
suspend operator fun invoke(onSuccess: (List) -> 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
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domain
class GetSpeakers(val api: SessionizeAPI, val dao: SpeakerDao) {
suspend operator fun invoke(onSuccess: (List) -> 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
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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
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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()
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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
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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)
fun onSpeakersDataFailed(e: Exception)
}
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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
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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
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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
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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
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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
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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
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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
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No content
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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
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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
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platform specific
expect object PlatformServiceLocator {
val httpClientEngine: HttpClientEngine
val databaseEngine: ScheduleDb
}
commonMain
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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
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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
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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
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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
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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){
setup(list)
…
multiplatform
network
database
android
parser
view
platform
specific
presenter
presenter
domain
model
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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){
setup(list)
…
multiplatform
network
database
android
parser
view
platform
specific
presenter
presenter
domain
model
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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)
}
}
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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
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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)
…
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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)
…
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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
}
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how much sharing?
what makes sense for your app
kotlin
multiplatform
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conclusions
don’t forget to bring your own towel.
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team structure
Kotlin Multiplatform
android iOS
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team structure
Kotlin Multiplatform
android iOS
mobile backend
documentation
tests
clean API
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(impressions)
Kotlin Multiplatform
I could just focus on doing what I know best - UI. I have
no idea how things are being done in the backend, yet I
know that when I ask for data I receive it.
- iOS Developer
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- 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
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- 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 simple update can break your builds
- lookout for plugins/ libraries updates
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- 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
- On cross platform 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
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- 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
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- Ktor (networking)
- Kotlinx.Coroutines
- Kotlin.Serialization
- SqlDelight (database)
- Multiplatform Settings
- Stately (state management)
(libraries)
more information
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- Kotlinconf App
- Droidcon Kotlin
- KaMP Kit
- Sudoku Playground
- PeopleInSpace
- Kotlin Game Of Life
- WorkoutMPP
(cool projects to follow)
more information
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- 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
- Android Makers Paris
Intégrer plusieurs libraires Kotlin Native dans vos apps Android/iOS (April 21st)
(useful links)
more information
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@cafonsomota
so long and thanks for all the fish
medium.com/@cafonsomota
github.com/cmota/AndroidMakers