Kotlin Multiplatform

Transcript

1. Meet Kotlin
   Multiplatform Mobile
   KMM for short
   Loveleen Kaur
   Senior Engineer (Astrotalk)
   Google Android Educator
   

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2. Who am I?
   ● Loveleen Kaur
   ● Senior Engineer - Android @ Astrotalk
   ● Core Team Member @ Google Developer Groups Chandigarh
   ● Co-Organizer @ Kotlin Chandigarh User Group
   ● Android Educator @ Android Educators Community India
   ● Phd Research Scholar
   ● Technical Speaker
   ● Develop Mobile Applications
   ● Happy Android Developer :)
   

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3. Questions I will try to answer
   -What is the difference between KMM and other multiplatform
   solutions like a flutter, react native, etc?
   -Is this a good solution for your business and why we thought it is
   a good decision for us?
   -How does iOS read the shared module?
   -How much code can we actually share?
   -What are the most important libraries and what these are doing?
   -Is KMM production ready?
   -Pros and cons of KMM
   

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4. Cross-platform mobile framework popularity
   

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5. Cross-platform mobile framework popularity
   

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6. Google trends
   

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7. Share code
   jvm
   Android
   iOS
   Linux
   macOS
   Windows
   JS
   watchOS
   tvOS
   

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8. KMM
   First Multiplatform
   Kotlin 1.2 November 2017
   Announced August 2020
   

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9. Why we choose KMM
   • Small team
   • Business logic in one place
   • iOS needed refactor
   

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10. KMM, the PoC
    • Configuration is tricky, but manageable
    • Things that works on android, do not need to
    work on iOS
    • One repo vs 3 repos
    • iOS simulator != iOS real device
    • Sample project != big project
    

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11. Networking October 2021
    

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12. January 2022
    Networking
    Persistance
    Models
    

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13. March 2022
    Networking
    Persistance
    Models
    Repositories
    UseCases
    

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14. June/July 2022
    Networking
    Persistance
    Models
    Repositories
    UseCases
    View Models
    UI layer
    

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15. Share
    code
    Domain
    Repositories
    Persistance Networking
    ViewModels
    Presentation
    Business(Kotlin)
    Framework(iOS,
    Android)
    

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16. KMM libraries
    137 libraries
    KTOR
    KOIN
    SQLdelight
    Multiplatform settings
    kotlinx.serialization
    kotlinx.datetime
    BuildKonfig
    Moko-resources
    

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17. Networking with KTOR
    • open-source
    • lightweight
    • powered by coroutines
    • Build by JetBrains
    

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18. Networking with KTOR
    fun createHttpClient(httpClientEngine: HttpClientEngine, logger: Logger) =
    HttpClient(httpClientEngine) {
    defaultRequest {
    url.protocol = URLProtocol.HTTPS url.host =
    BuildKonfig.BASE_URL parameter("apikey",
    BuildKonfig.API_KEY)
    parameter("Accept-Language", languageCode ?: "en")
    }
    install(ContentNegotiation) { json(json) }
    install(Logging) { this.logger =
    logger level = logLevel
    }
    }
    

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19. Networking with KTOR
    fun createHttpClient(httpClientEngine: HttpClientEngine,
    logger: Logger) =
    HttpClient(httpClientEngine) {
    defaultRequest {
    url.protocol = URLProtocol.HTTPS url.host =
    BuildKonfig.BASE_URL parameter("apikey",
    BuildKonfig.API_KEY)
    parameter("Accept-Language", languageCode ?: "en")
    }
    install(ContentNegotiation) { json(json) }
    install(Logging) {
    this.logger = logger level
    = logLevel
    }
    }
    OkHttp + Retrofit
    Retrofit.Builder().baseUrl()
    In interceptor:
    chain.request().header()
    

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20. fun createHttpClient(httpClientEngine: HttpClientEngine, logger: Logger) =
    HttpClient(httpClientEngine) {
    defaultRequest {
    url.protocol = URLProtocol.HTTPS
    url.host = BuildKonfig.BASE_URL
    parameter("apikey", BuildKonfig.API_KEY)
    parameter("Accept-Language", languageCode ?: "en")
    }
    install(ContentNegotiation) { json(json) }
    install(Logging) {
    this.logger = logger
    level = logLevel
    }
    }
    OkHttp + Retrofit
    Retrofit.Builder().baseUrl(
    )
    In interceptor:
    chain.request().header(
    )
    .addConverterFactory(jsonConverter)
    Networking with KTOR
    

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21. fun createHttpClient(httpClientEngine: HttpClientEngine, logger: Logger) =
    HttpClient(httpClientEngine) {
    defaultRequest {
    url.protocol = URLProtocol.HTTPS
    url.host = BuildKonfig.BASE_URL
    parameter("apikey", BuildKonfig.API_KEY)
    parameter("Accept-Language", languageCode ?: "en")
    }
    install(ContentNegotiation) { json(json) }
    install(Logging) {
    this.logger = logger
    level = logLevel
    }
    }
    OkHttp + Retrofit
    Retrofit.Builder().baseUrl(
    )
    In interceptor:
    chain.request().header(
    )
    .addConverterFactory(jsonConverter)
    .addInterceptor(httpLoggingInterceptor)
    Networking with KTOR
    

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22. Http Client Engine Android.create()
    val logger = object : Logger {
    override fun log(message: String) {
    Log.i(tag, message)
    }
    }
    Darwin.create()
    Logger.DEFAULT
    Logger
    Networking with KTOR
    

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23. Actual/Expected
    

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24. Actual/Expected
    //common
    expect val httpEngine: HttpClientEngine expect val
    logger: Logger
    //androidMain
    actual val httpEngine = Android.create() actual val
    logger = object : Logger {
    override fun log(message: String) { Log.i(tag,
    message)
    }
    }
    //iosMain
    actual val httpEngine = Darwin.create() actual val
    logger = Logger.DEFAULT
    

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25. iOS and
    coroutines
    

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26. iOS and
    coroutines
    Async/Await
    RxSwift
    Combine
    Callbacks
    

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27. iOS
    Source: https://dev.to/touchlab/kotlin-coroutines-and-swift-revisited-j5h
    func createPublisher(flowAdapter: FlowAdapter) -> AnyPublisher {
    return Deferred>> {
    let subject = PassthroughSubject()
    let job = flowAdapter.subscribe(
    onEvent: { (item) in let _ = subject.send(item) },
    onError: { (error) in subject.send(completion: .failure(KotlinError(error))) },
    onComplete: { subject.send(completion: .finished) }
    )
    return subject.handleEvents(receiveCancel: {
    job.cancel(cause: nil)
    })
    }.eraseToAnyPublisher()
    }
    

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28. Shared
    iOS
    class FlowAdapter(
    private val scope: CoroutineScope,
    private val flow: Flow
    ) {
    fun subscribe(
    onEvent: (T) -> Unit,
    onError: (Throwable) -> Unit,
    onComplete: () -> Unit
    ): Job =
    flow
    .onEach { onEvent(it) }
    .catch { onError(it) }
    .onCompletion { onComplete() }
    .launchIn(scope)
    }
    

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29. SSOT for
    resources
    

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30. Resources
    Moko-resources
    https://github.com/icerockdev/moko-resources
    

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31. Strings.xml
    Resources
    Cancel
    Current location
    Yesterday
    

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32. Compose
    Resources
    stringResource(id = SharedRes.strings.my_string.resourceId)
    Swift/SwiftUI
    let string = MR.strings().my_string.desc().localized()
    LocalizedStringKey(MR.strings().email.resourceId)
    

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33. Resources
    Common
    val stringDesc = StringDesc.Resource(SharedRes.strings.airlypedia_title)
    

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34. Resources
    Common
    val stringDesc = StringDesc.Resource(SharedRes.strings.airlypedia_title)
    .toString(context)
    

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35. Resources
    Common
    val stringDesc = StringDesc.Resource(SharedRes.strings.airlypedia_title)
    .toString(context) .localized()
    

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36. Resources
    Common
    val stringDesc = StringDesc.Resource(SharedRes.strings.airlypedia_title)
    expect fun ResourceStringDesc.getText(): String
    

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37. Resources
    Common
    val stringDesc = StringDesc.Resource(SharedRes.strings.airlypedia_title)
    expect fun ResourceStringDesc.getText(): String
    actual fun ResourceStringDesc.getText(): String =
    this.toString(appContext)
    

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38. Resources
    Common
    val stringDesc = StringDesc.Resource(SharedRes.strings.airlypedia_title)
    expect fun ResourceStringDesc.getText(): String
    actual fun ResourceStringDesc.getText(): String =
    this.toString(appContext)
    actual fun ResourceStringDesc.getText(): String =
    this.localized()
    

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39. How to read KMM in platforms?
    

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41. dependencies {
    implementation(project(":shared"))
    }
    

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42. dependencies {
    implementation(project(":shared"))
    }
    

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43. dependencies {
    implementation(project(":shared"))
    }
    New Run Script Phase
    

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44. dependencies {
    implementation(project(":shared"))
    }
    New Run Script Phase
    https://kotlinlang.org/docs
    

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45. Next steps
    • Use async/await in iOS for suspend functions
    • Try crashlytics, analytics, etc
    • Use KMM for web app
    • Share more assets
    

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46. iOS & Android everyday
    

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47. iOS & Android using KMM
    

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48. Is it ready for production?
    

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49. KMM - Pros and
    Cons
    • 100% Native
    • Android developers know
    Kotlin and Gradle
    • Optional
    • Still in Alpha
    

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50. KMM - Pros and
    Cons
    • 100% Native
    • Android developers know
    Kotlin and Gradle
    • Optional
    • Still in Alpha
    • UI written separately
    

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51. Meet Kotlin
    Multiplatform Mobile
    Thanks for listening!
    Loveleen Kaur
    Senior Engineer (Astrotalk)
    Google Android Educator
    

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