Kotlin Multiplatform & Compose Multiplatform - Starter kit for pragmatics

Kotlin Multiplatform &
Compose Multiplatform
Starter kit for pragmatics
Andrei Dotsenko

Android fan
Work with Android
for the last 10 years
Geek and digger
Like to play around
with new technologies
Traveler
Passionate about
discovering new places
About me
Love tech communities
Has been part of several
conferences and
meetups. GDG organizer
Family guy
Most of my free time
belongs to 󰙐🐶󰘲
Lived in different cultures
Has been living in
󰎴󰑆󰏃󰐮
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❤
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Table of contents
● Key concepts and terminology
● How does that work
● KMP & Compose - current state
● Where to start
● Building blocks
● Limitations & Challenges
● Resources

Key concepts and terminology
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Key concepts and terminology
● Kotlin Multiplatform
● KMP (or KMM?!)
● Jetpack Compose
● Compose Multiplatform
��

How does that work
Kotlin Multiplatform

How does that work
Kotlin Multiplatform for mobile targets

How does that work
Jetpack Compose (Android)

Not a new kid on the block anymore

How does that work
Compose Multiplatform

How does that work
expect-actual concept

KMP & Compose - current state
��

Where to start
https://kmp.jetbrains.com/
https://github.com/Kotlin/kdoctor

Pre-configured project, that is
ready for writing shared code
Pre-configured build configurations
for both Android and iOS

Xcode project (with info.plist, UIkit/SwiftUI entry point)
Shared Kotlin code is added as .framework

Android-specific code (manifest, activity, etc.)

Building blocks
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Network client
DB / key-value storage
Navigation
Resources / localization
ViewModels
Native look & feel
Maps
DI

Network
��
https://github.com/terrakok/kmp-awesome

Network
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● Ktor - mature network client by JetBrains.
Feature-rich (HTTP requests, Bearer authentication, web sockets, etc.)
● Kotlinx.serialization - multi-format (JSON, Protobuf and many more)
reflectionless serialization
● Ktorfit - Ktor-based REST API client (syntax mirrors Retrofit)

Network client
Navigation
ViewModels
Native look & feel
Maps
DI
✅
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Building blocks

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● SQLDelight - powerful SQL DB, made by Block (ex. Square)
● Realm - NoSQL database
● Multiplatform Settings - key-value data storage, supports KeyChain.
Wrapper for SharedPreferences and NSUserDefaults.

Building blocks
Network client
Navigation
ViewModels
Native look & feel
Maps
DI
✅
��
✅

Navigation & ViewModels
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● Compose Multiplatform Navigation - official solution from Jetbrains.
Familiar APIs (mirrors Jetpack Compose Navigation), but experimental and has
limitations (no deep links support, limited back handler)
● Compose Multiplatform ViewModel - official solution from Jetbrains.
Familiar APIs (mirrors Android ViewModel), but experimental and has limitations
(additional setup required for iOS and web targets)
● Decompose - library for breaking down your code into lifecycle-aware business
logic components (aka BLoC), with routing functionality.
● PreCompose - navigation, ViewModel, inspired by Jetpack Lifecycle,
ViewModel, LiveData and Navigation, provides similar (or even the same)
components

Building blocks
Network client
Navigation
ViewModels
Native look & feel
Maps
DI
✅
��
✅
✅
✅

Dependency Injection
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● Koin - lightweight dependency injection framework. Koin is a DSL, a
light container and a pragmatic API
● Kodein - very simple and yet very useful dependency retrieval
container

Building blocks
Network client
Navigation
ViewModels
Native look & feel
Maps
DI
✅
��
✅
✅
✅
✅

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● Compose Multiplatform Resources - official solution from Jetbrains.
Experimental, has several limitations (big raw files, multi module).
Supports language, density and theme qualifiers. Custom fonts too.
● MOKO Resources - system resources manager that provides access
to the resources on iOS & Android with the support of the default
system localization

Building blocks
Network client
Navigation
ViewModels
Native look & feel
Maps
DI
✅
��
✅
✅
✅
✅ (almost)
✅

Native look & feel
��🏼
Compose Multiplatform release changelogs:

Native look & feel
��🏼
Compose Cupertino - provides various UI components for
making native-looking iOS applications, including:
● cupertino - Compose Multiplatform implementation of iOS-like
Cupertino theme and widgets
● cupertino-native - UIKit native wrappers for Cupertino Widgets.
Allows to seamlessly use some UIKit widgets for iOS
● cupertino-adaptive - adaptive theme and wrappers for Cupertino
and Material3 widgets.
● cupertino-icons-extended - more than 800 most used
monochrome Apple SF Symbols as Compose ImageVectors
● cupertino-decompose - iOS-like swipe-back animation for the
'predictive back' navigation feature (native-feeling or truly native page
transitions and swipe gestures).

Building blocks
Network client
Navigation
ViewModels
Native look & feel
Maps
DI
✅
��
✅
✅
✅
✅ (almost)
✅
��🏼

Maps
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https://github.com/ShreyashKore/wonderous_compose
Wonderous Compose - is a port of Wonderous (Flutter) in Compose
Multiplatform.
Map View demonstrates how KMP and Compose's interoperability
layer can be used to embed native UIs in Compose.
● For Android - Google Map compose library is used.
● For IOS - MKMapView is used.
● For web - Wasm Html interop library is used to draw DOM elements on canvas.
● For desktop - uses OpenStreetMap data to draw map tiles on Compose Canvas.

Building blocks
Network client
Navigation
ViewModels
Native look & feel
Maps
DI
✅
��
✅
✅
✅
✅ (almost)
✅
��🏼
��

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Pro tip
Unofficial wizard. Creates the
project with preselected
dependencies
https://terrakok.github.io/Compose-Multiplatform-Wizard/

Limitations & Challenges
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Limitations & Challenges
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● Platform-specific APIs (e.g. Share Extension on iOS, in-app purchases, etc.)
No magic here 󰤇
● Compose Multiplatform iOS performance != native iOS performance
● Configuring build scripts and managing dependencies is an adventure
● Mac is required for building iOS or MacOS targets
● Wouldn’t recommend for beginners with no Android or iOS experience
● Under active development
● Best practices have not yet been settled
● (sometimes) It’s hard to convince iOS devs to try it out

Resources
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● https://www.jetbrains.com/help/kotlin-multiplatform-dev/
● https://github.com/Kotlin/kdoctor
● https://github.com/ShreyashKore/wonderous_compose
● https://github.com/terrakok/kmp-awesome
● https://github.com/touchlab
● https://terrakok.github.io/Compose-Multiplatform-Wizard/
● https://youtu.be/FWVi4aV36d8?si=AfMmlVhkojU7j5j6
● https://youtu.be/EKFdYgjCNOs
● https://medium.com/@uwaisalqadri/kotlin-multiplatform-mobile-concept-of-expect-
actual-f967d2e948ce
● https://t.me/kotlinmpp

Thank you!
��
@dosssik
linkedin.com/in/andrei-dotsenko

Kotlin Multiplatform & Compose Multiplatform - Starter kit for pragmatics

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