A hitchhiker's guide to Kotlin MultiPlatform

Where other technologies abstract away or completely replace platform-specific app development, Kotlin Multiplatform is complementary to existing platform-specific technologies and is geared towards replacing platform-agnostic business logic. It’s a new tool in the toolbox as opposed to replacing the toolbox, this talk would take you on a hitch-hiking journey across multiple platforms such as web , desktop and mobile apps all using KMP. We would pickup on where to get started , whats the future like and how to build faster with tips and tricks of the trade.

Transcript

1. A hitchhiker's guide
   to Kotlin
   MultiPlatform
   Google Developers
   

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2. Android GDE

   🛠 Individual Consultant

   🔊 Speaker

   🌎 Globe Trotter

   🍻 Beer enthusiast
   🎯https:/
   /androiddev.social/@aditlal
   🔗aditlal.dev
   

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4. a wild idea to build apps pops!
   develop for Android and iOS
   

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5. ‣ hire a team - Android and iOS
   ‣ de
   fi
   ne requirements
   ‣ plan roadmap for development
   ‣ develop and maintain and test apps
   ‣ production validation
   ‣ cross-check parity among both platforms
   

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6. native
   ~2x the team
   the cost
   time spent in meetings
   time spent on development
   time spent on testing
   time spent on bug
   fi
   xing
   

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7. a wild idea to build apps pops!
   develop for Android and iOS
   

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8. a wild idea to build apps pops!
   and web
   develop for Android and iOS
   

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9. native + web
   ~3x the team
   the cost
   time spent in meetings
   time spent on development
   time spent on testing
   time spent on bug
   fi
   xing
   

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12. let’s
    fi
    nd a solution that works on all
    platforms.
    

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13. 2006 2008 2011 2012 2013 2015 2017 2018
    . . . . . . .
    

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14. Cross-platform advantages
    

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15. Cross-platform advantages
    • smaller team/s
    • typically half of the cost needed on native
    • small learning curve for web developers
    

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16. Cross-platform advantages
    dis
    • Locked to the framework implementation of UI
    - new updates from the OS will take time to adapt
    • performance is not on par to native
    • One may end up also writing native code alongside
    • OS / device features are dependent on the fw
    support
    

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17. how do we have the best of
    both worlds?
    

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

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19. Kotlin
    • developed by JetBrains
    • open source
    • concise, safe, interoperable, dev tool-friendly
    • Supported/used by Google for Android
    Development
    • It is so much more than “just for Android”
    

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20. Kotlin
    K
    otlin multiplatform
    Using kotlin in projects to
    target more than one platform
    

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21. Kotlin multiplatform
    “Shared UI is a history of pain
    and failure. Shared logic is the
    history of computers.”

    

    - Kevin Galligan
    

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22. Kotlin multiplatform
    - language features
    - kotlin
    fi
    rst!
    - low risk
    - you decide what’s worth to share across projects
    - interoperability
    - consistency across platforms
    - strong community support
    

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23. Kotlin multiplatform
    /kot · lin mul · ti · plat · form /
    
    
    / kät' lin malti' platfôrm, kät'lin melti'platfôrm/
    
    
    noun
    optional, natively-integrated, open-source, code sharing platform, based on
    the popular, modern language kotlin. facilitates non-ui logic availability on
    many platforms.
    

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24. Kotlin multiplatform
    

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25. Kotlin multiplatform
    

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26. Kotlin multiplatform
    

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27. Kotlin multiplatform
    but how can they expect to communicate?
    

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28. Kotlin multiplatform
    but how can they expect to communicate?
    expect
    declared at common module 

    actual
    declared at android module
    declared at iOS module
    declared at ...
    

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29. Kotlin multiplatform
    Platform specif
    i
    c
    names?
    

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30. Kotlin multiplatform
    Platform | common
    

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31. Kotlin multiplatform
    commonMain
    src/commonMain/sample/Platform.kt
    
    
    expect object Platform {
    
    
    val name: String
    
    
    }
    

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32. Kotlin multiplatform
    src/commonMain/sample/Platform.kt
    
    
    expect object Platform {
    
    
    val name: String
    
    
    }
    

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33. Kotlin multiplatform
    src/commonMain/sample/Platform.kt
    
    
    expect object Platform {
    
    
    val name: String
    
    
    }
    targets: android and iOS or macOS

    de
    fi
    ne actual on android
    de
    fi
    ne actual on iOS

    de
    fi
    ne actual on macOS
    

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34. Kotlin multiplatform
    src/androidMain/sample/Platform.kt
    actual object Platform {
    
    
    actual val name: String = "Android"
    
    
    }
    platform-dependent code
    

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35. Kotlin multiplatform
    platform-dependent code
    actual object Platform {
    
    
    actual val name: String = “iOS"
    
    
    }
    src/iOSMain/sample/Platform.kt
    

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36. Kotlin multiplatform
    src/androidMain/sample/Platform.kt
    actual object Platform {
    
    
    actual val name: String = "Android"
    
    
    }
    platform-dependent code
    actual object Platform {
    
    
    actual val name: String = “iOS"
    
    
    }
    src/iOSMain/sample/Platform.kt
    

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37. Kotlin multiplatform
    platform-dependent code
    actual object Platform {
    
    
    actual val name: String = “macOS”
    
    
    }
    src/macosMain/sample/Platform.kt
    

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38. Kotlin multiplatform
    platform-dependent code
    import io.ktor.*
    fun main() {
    embeddedServer(Netty, 9090) {
    routing {
    get("/hello") {
    call.respondText("Hello, API!")
    }
    }
    }.start(wait = true)
    }
    src/jvmMain/kotlin/Server.kt
    

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39. Kotlin multiplatform
    

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40. Kotlin multiplatform
    Actual needs to match
    because obviously it does
    

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41. Kotlin multiplatform
    

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42. Kotlin multiplatform
    

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43. Common

    Kotlin
    Kotlin/JS
    JS code
    Kotlin/JVM
    JVM code
    Kotlin/Native
    Native code
    Kotlin multiplatform
    

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44. Kotlin multiplatform
    Kotlin
    How much do we share
    Multiplatform
    What makes most sense
    

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45. Kotlin multiplatform
    - strong community
    - a lot of people are using kotlin nowadays
    - Google and JetBrains are pushing Kotlin exclusively
    - you can ask questions directly at https://kotlinlang.slack.com
    conclusions
    

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46. Kotlin multiplatform
    - 2x faster to develop your features business logic
    - 2x faster writing unit tests
    - One tech stack
    - consistency achieved across platforms
    conclusions
    

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47. Kotlin multiplatform
    - start small, don’t try to reach 100% of shared logic
    - be extremely careful with all updates
    - IDEA, JDK, kotlin, libraries - everything.
    - keep versioning in mind
    Suggestions
    

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48. Kotlin multiplatform
    Kotlin Slack
    Kotlin Of
    fi
    cial
    Kotlin Training
    Kotlin by:
    - https://jakewharton.com/presentations/
    - http://antonioleiva.com/kotlin
    Resources
    

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49. Kotlin multiplatform
    https://github.com/joreilly/PeopleInSpace

    

    About
    Kotlin Multiplatform project with SwiftUI, Jetpack Compose, Wear Compose,
    Compose for Desktop, Compose for Web and Kotlin/JS + React clients along
    with Ktor backend.
    Resources
    

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50. Thats all folks!
    https://cal.com/adit/30min
    🎯https:/
    /androiddev.social/@aditlal
    🔗aditlal.dev
    

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