SHIPPING MULTIPLATFORM ON IOS & ANDROID BEN ASHER ALEC STRONG - - PowerPoint PPT Presentation

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SHIPPING MULTIPLATFORM ON IOS & ANDROID BEN ASHER ALEC STRONG - - PowerPoint PPT Presentation

Sep 23, 2022 202 likes •1.17k views

SHIPPING MULTIPLATFORM ON IOS & ANDROID BEN ASHER ALEC STRONG @benasher44 @strongolopolis Copenhagen Denmark SHIPPING MULTIPLATFORM ON IOS & ANDROID BEN ASHER ALEC STRONG @benasher44 @strongolopolis Copenhagen Denmark Markups

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Copenhagen Denmark

SHIPPING MULTIPLATFORM ON IOS & ANDROID BEN ASHER ALEC STRONG

@benasher44 @strongolopolis

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Copenhagen Denmark

SHIPPING MULTIPLATFORM ON IOS & ANDROID BEN ASHER ALEC STRONG

@benasher44 @strongolopolis

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Link to another sheet Markups

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History

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Live Info

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Championed on iOS ~15 across Android and iOS Construction Championed on Android ~30 across Android and iOS Financial Services

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Offline Sync System Search Business Logic

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Business Logic Models

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MPP

Business Logic Models

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MPP

Business Logic Models

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MPP

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MPP Kotlin/Native

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New tools New language Uneven ecosystem

🌯🌯🌯 🌯🌯🌯

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Adopting cross-platform in your app has a cost

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What is the value that makes it worth the effort?

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Diverging Sync Systems

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Existing Shared Code

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What tools will your cross-platform solution need What is the common goal all stakeholders have

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What else?

No JNI

  • n Android

Obj-C
 Interop Not New For Android Community Jetbrains

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Common Questions

Kotlin/Native relies on Obj-C? What about Swift?

Obj-C header is well-annotated for Swift This is the status quo for Apple’s own frameworks

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Common Questions

What about performance?

Same performance expectations on Android Can drop into C if needed on iOS

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Common Questions

What about value types?

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Common Questions

There’s a garbage collector? But there’s no JVM, right? Bacon’s Algorithm for GC

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Common Questions

What libraries can we use for mpp?

JVM Distributions are incomplete Special multiplatform distributions K/N ABI instability (klib)

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Common Questions

What is “common” code?

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commonMain iosMain androidMain iOS - .framework Android - .aar

Library Outputs Library Source Sets

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commonMain iosMain androidMain iOS - .framework Android - .aar

Library Outputs Library Source Sets Code expect class Lock actual class Lock actual class Lock

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expect class Lock actual class Lock actual class Lock

commonMain iosMain androidMain iOS - .framework Android - .aar

Library Outputs Library Source Sets

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commonMain iosMain androidMain iOS - .framework Android - .aar

Library Outputs Library Source Sets

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commonMain iosMain androidMain iOS - .framework Android - .aar

Library Outputs Library Source Sets

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commonMain iosMain androidMain iOS - .framework Android - .aar

Library Outputs Library Source Sets

windowsMain Windows - .dll

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Is it platform agnostic? commonMain

Yes No

Will other common code use it?

Yes No

Platform

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Is it platform agnostic? commonMain

Yes No

Will other common code use it?

Yes No

Platform

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Is it platform agnostic?

No

Will other common code use it? commonMain

Yes

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expect class DatabaseFactory { internal fun createSqliteDriver(): SqlDriver }

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Is it platform agnostic?

No

Will other common code use it?

No

Platform

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sourceSets {A commonMain {B}C androidLibMain {D}E iosLibMain {F}G }H

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sourceSets {A commonMain {B}C androidLibMain {D dependencies {I api project(‘:protos') }J }E iosLibMain {F}G }H

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fun SearchQueries.insert(entity: SyncEntity) entity: SyncEntity

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sourceSets {A commonMain {B}C androidLibMain {D}E iosLibMain {F}G }H

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sourceSets {A commonMain {B}C androidLibMain {D}E }H

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Is it platform agnostic? commonMain

Yes

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fun search(terms: String): List<Search>?

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commonMain iosMain androidMain

Library Source Sets

Host
 Application

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Host
 Application

Talks to backend API Talks to existing application state

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Host
 Application commonMain

Library Initialization

Library defines interface App provides implementation

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Highly platform-specific Backend API Hosts Current user’s credential

Case Study: Networking

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Make an API request Receive an async response Interface can be re-implemented later

MPP Life Hack: Interface Network

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interface Network { /** * Makes an API request */ fun makeRequest( host: APIHost, request: Request, completion: (Request.Response) -> Unit ): NetworkDisposable }

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interface Network { /** * Makes an API request */ fun makeRequest( host: APIHost, request: Request, completion: (Request.Response) -> Unit ): NetworkDisposable } host: APIHost Plain enum of names of the hosts– no URL handling required

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interface Network { /** * Makes an API request */ fun makeRequest( host: APIHost, request: Request, completion: (Request.Response) -> Unit ): NetworkDisposable } request: Request data class:

  • String path and body,
  • query params dict
  • enum method (GET, POST, etc.)
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interface Network { /** * Makes an API request */ fun makeRequest( host: APIHost, request: Request, completion: (Request.Response) -> Unit ): NetworkDisposable } completion: (Request.Response) -> Unit sealed class w/ different response types:

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interface Network { /** * Makes an API request */ fun makeRequest( host: APIHost, request: Request, completion: (Request.Response) -> Unit ): NetworkDisposable } NetworkDisposable Interface with a cancel() method

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suspend fun Network.makeRequest( host: APIHost, request: Request ): Request.Response

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Concurrency in commonMain

commonMain iosMain androidMain

expect fun <T> T.freeze(): T actual fun <T> T.freeze(): T = this actual fun <T> T.freeze(): T = freeze()

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Shipping Internally

commonMain iosMain androidMain Host
 Application

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commonMain iosMain androidMain Host
 Application Host
 Application

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commonMain iosMain androidMain Host
 Application Host
 Application

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Pros Cons

Minimal change for android Seamless local development Single source of truth Host dependencies Two build environments for iOS CI Nightmare

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commonMain iosMain androidMain Host
 Application Host
 Application

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commonMain iosMain androidMain Host
 Application Host
 Application

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commonMain commonMain iosMain androidMain Host
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 Application

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commonMain iosMain androidMain Host
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 Application commonMain

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Pros Cons

Minimal change for android Seamless local development Host dependencies Two build environments for iOS CI Nightmare for iOS Out of sync code

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commonMain iosMain androidMain Host
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 Application

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commonMain iosMain androidMain Host
 Application Host
 Application

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Pros Cons

CI is fast Encourages unit test coverage Single source of truth Breaking changes are painful Need good CD setup Debugging decoupled repos

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commonMain iosMain androidMain Host
 Application Host
 Application

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commonMain iosMain Host
 Application Host
 Application androidMain

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commonMain androidMain Host
 Application Host
 Application

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Shipping Externally Test Crashing!

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Shipping Externally

fun crash() { (null as String?)!! }

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Shipping Externally

setUnhandledExceptionHook()

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Shipping Externally What happens if a Worker crashes?

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Define your project’s goals Be thoughtful growing your codebase Avoid solving general muliplatform problems Get your CI and dev setup working early Join us in Kotlin slack

Review

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#KotlinConf

THANK YOU AND REMEMBER TO VOTE

Ben Asher @benasher44 Alec Strong @Strongolopolis