D-KMP architecture - official sample

This is the official sample of the D-KMP architecture, where "D" stands for Declarative UI and "KMP" stands for Kotlin MultiPlatform. It presents a simple master/detail app, for Android, iOS and Desktop. 
The business logic is fully shared (and written in Kotlin). The UI is platform-specific: Compose for Android and Desktop, SwiftUI for iOS. 
 
UPDATE MAY 2025: 
This repository about the D-KMP architecture will be kept online, but it won't be updated anymore. 
The D-KMP architecture was conceived in 2020, when nobody expected that Compose would have become a first-class UI toolkit also for iOS. Now Compose MultiPlatform is stable and production-ready for Android, iOS and Desktop, so sharing both the business logic and the UI using Compose MultiPlatform (CMP) has become the preferred KMP solution. 
All information about writing apps with Compose MultiPlatform can be found on the official CMP website by JetBrains. 
 
UPDATE NOVEMBER 2025: 
Navigation3 is now finally available also to CMP, providing the very much awaited CMP-optimized navigation library! 
Google is now also mentioning Compose Multiplatform on the KMP section of the Android website, listing all the Jetpack libraries available for KMP/CMP. The path cannot be clearer. It doesn't make anymore sense to duplicate the UI for each platform. Compose has all that's needed for a robust and maintanable multiplatform app. By the end of 2026, Compose is also expected to become production ready for Web/Wasm.

Key features of the D-KMP architecture:

it uses the latest declarative UI toolkits: Compose for Android and SwiftUI for iOS
it fully shares the ViewModel (including navigation logic and data layer) via Kotlin MultiPlatform
coroutine scopes are cancelled/reinitialized automatically, based on the current active screens and the app lifecycle (using LifecycleObserver on Android and the SwiftUI lifecycle on iOS)
it implements the MVI pattern and the unidirectional data flow
it implements the CQRS pattern, by providing Command functions (via Events and Navigation) and Query functions (via StateProviders)
it uses Kotlin's StateFlow to trigger UI layer recompositions
the navigation state is processed in the shared code, and then exposed to the UI layer:
- on SwiftUI it seamlessly integrates with the new iOS 16 navigation patterns (NavigationStack and/or NavigationSplitView)
- on Compose it's a "remembered" data class which works on any platform (unlike Jetpack Navigation, which only works on Android)

you can find more info on these articles:

D-KMP sample now leverages iOS 16 navigation (february 2023)
The future of apps:
Declarative UIs with Kotlin MultiPlatform (D-KMP) (november 2020)

Data sources used by this sample:

webservices (using Ktor Http Client)
local db (using SqlDelight)
local settings (using MultiplaformSettings)

these are other data sources, not used by this sample, for which popular KMP libraries exist:

realtime db (using Firestore)
graphQL (using Apollo GraphQL)
device bluetooth (using Kable)
etc...

Instructions to write your own D-KMP app:

If you want to create your own app using the D-KMP Architecture, here are the instructions you need:

SHARED CODE:

View Model

:hammer_and_wrench: in the viewmodel/screens folder: create a folder for each screen of the app, containing these 3 files (as shown in the sample app structure above):
- screenEvents.kt, where the event functions for that screen are defined
- screenInit.kt, where the initialization settings for that screen are defined
- screenState.kt, where the data class of the state for that screen is defined
:hammer_and_wrench: in the NavigationSettings.kt file in the screens folder, you should define your level 1 navigation and other settings
:hammer_and_wrench: in the ScreenEnum.kt file in the screens folder, you should define the enum with all screens in your app
:white_check_mark: the ScreenInitSettings.kt file in the screens folder doesn't need to be modified
:white_check_mark: the 6 files in the viewmodel folder (DKMPViewModel.kt, Events.kt, Navigation.kt, ScreenIdentifier.kt, StateManager.kt, StateProviders.kt) don't need to be modified
:white_check_mark: also DKMPViewModelForAndroid.kt in androidMain and DKMPViewModelForIos.kt in iosMain don't need to be modified

Data Layer

:hammer_and_wrench: in the datalayer/functions folder: create a file for each repository function to be called by the ViewModel's StateReducers
:hammer_and_wrench: in the datalayer/objects folder: create a file for each data class used by the repository functions
:hammer_and_wrench: in the datalayer/sources folder: create a folder for each datasource, where the datasource-specific functions (called by the repository functions) are defined
:white_check_mark: the datalayer/Repository.kt file should be modified only in case you want to add an extra datasource

PLATFORM-SPECIFIC CODE:

Android

:white_check_mark: the App.kt file doesn't need to be modified
:white_check_mark: the MainActivity.kt file doesn't need to be modified
The composables are used by both Android and Desktop apps:
- :hammer_and_wrench: the Level1BottomBar.kt and Level1NavigationRail.kt files in the navigation/bars folder should be modified to custom the Navigation bars items
- :white_check_mark: the TopBar.kt file in the navigation/bars folder doesn't need to be modified
- :white_check_mark: the OnePane.kt and TwoPane.kt files in the navigation/templates folder don't need to be modified
- :white_check_mark: the HandleBackButton.kt file in the navigation folder doesn't need to be modified
- :white_check_mark: the Router.kt file in the navigation folder doesn't need to be modified
- :hammer_and_wrench: in the ScreenPicker.kt file in the navigation folder, you should define the screen composables in your app
- :hammer_and_wrench: in the screens folder: create a folder for each screen of the app, containing all composables for that screen
- :white_check_mark: the MainComposable.kt file doesn't need to be modified

iOS

:hammer_and_wrench: the Level1BottomBar.swift and Level1NavigationRail.swift files in the composables/navigation/bars folder should be modified to custom the Navigation bars items
:white_check_mark: the TopBar.swift file in the composables/navigation/bars folder doesn't need to be modified
:white_check_mark: the OnePane.swift and TwoPane.swift files in the composables/navigation/templates folder don't need to be modified
:white_check_mark: the Router.swift file in the composables/navigation folder doesn't need to be modified
:hammer_and_wrench: in the ScreenPicker.swift file in the views/navigation folder, you should define the screen composables in your app
:hammer_and_wrench: in the views/screens folder: create a folder for each screen of the app, containing all SwiftUI views for that screen
:white_check_mark: the App.swift file doesn't need to be modified
:white_check_mark: the AppObservableObject.swift file doesn't need to be modified

Desktop

:white_check_mark: the main.kt file doesn't need to be modified
The composables are used by both Android and Desktop apps:
- look at the description on the Android section above