Files
simplex-chat/apps/multiplatform
Narasimha-sc 2a7eb7eed2 fix the review's findings and cut the remaining API surface
Correctness.

The one-time link picker's profile list was keyed on the active user as well as the
count. That defeats the "don't change order after a user was selected" behaviour its own
comment protects - changeActiveUser_ sets currentUser first and only then reloads chats,
so the list visibly re-sorted and stayed re-sorted for the whole of getUserChatData - and
it was redundant: the count alone covers a profile being created from the picker.

iOS, compose picker: the old-core fallback relied on the user switch tearing this view
down, which only happens when the switch succeeded. If it threw, the form was left open
over a profile that already existed, and the only way out was to swipe it away. It is now
dismissed unconditionally.

iOS: alerts raised right after a sheet is dismissed are presented on a controller that is
going away and are dropped. The 0.5s wait was applied only to the old-core path, while the
ordinary reassignment failures - the ones that actually happen - went unguarded.
alertAfterDismissal now covers all of them, in one place.

iOS: dropped the chatId write that Kotlin removed for the same reason two commits ago. It
is a no-op on the happy path, but not if something legitimately closed the chat meanwhile
- SimpleX lock re-auth clears it, and this would reopen the chat behind the lock screen.

iOS: the create-profile row is now gated on profileChangeProhibited, as every other row on
both platforms already was.

Surface.

apiCreateActiveUser takes keepActiveUser as a defaulted argument, exactly as it already
takes pastTimestamp, instead of a public wrapper plus a private helper. Two symbols fewer
on each platform, and every existing call site passes its arguments by name, so none of
them changes.

Reverted the activeOrder sort flip in the compose picker: it changes the order of an
existing screen for every user, is not needed for this feature, and with active_order 0
would push a newly created profile to the bottom. It deserves its own commit if wanted.

Also: apps/ios/spec/api.md tracks the command enum and had gone stale; the plan records
the two limits of the flag the review surfaced - it is ignored when there is no active
user, and active_order 0 ties rather than sorts last on migrated databases.
2026-08-06 17:27:35 +00:00
..
2023-06-29 12:53:11 +01:00
2026-01-24 17:59:46 +00:00

Android App Development

This is a guide to contributing to the develop of the SimpleX android and desktop apps.

Project Overview

This is the Kotlin Multiplatform (KMP) mobile and desktop client for SimpleX Chat, sharing code between Android and Desktop (JVM) platforms using Compose Multiplatform for UI.

Build Commands

# Android debug APK
./gradlew assembleDebug

# Android release APK
./gradlew assembleRelease

# Desktop distribution (current OS)
./gradlew :desktop:packageDistributionForCurrentOS

# Run desktop/JVM tests
./gradlew desktopTest

# Run Android instrumented tests (requires connected device/emulator)
./gradlew connectedAndroidTest

# Build native libraries for all platforms
./gradlew common:cmakeBuild -PcrossCompile

# Clean build
./gradlew clean

Architecture

Module Structure

  • common/ - Shared code (Compose UI, models, business logic)
    • src/commonMain/ - Cross-platform code
    • src/androidMain/ - Android-specific implementations
    • src/desktopMain/ - Desktop-specific implementations
  • android/ - Android app container
  • desktop/ - Desktop JVM app container

Key Components (common/src/commonMain/kotlin/chat/simplex/common/)

  • model/ChatModel.kt - Main state container with reactive properties (MutableState, MutableStateFlow)
  • model/SimpleXAPI.kt - API bindings to Haskell core library via FFI
  • platform/Core.kt - FFI interface to native libapp library
  • platform/ - Platform abstraction layer (expect/actual pattern for Android/Desktop specifics)
  • views/ - Compose UI screens organized by feature (chat, chatlist, call, usersettings, etc.)
  • ui/theme/ - Design system (colors, typography, shapes)

Native Integration

The app calls into a Haskell core library via JNI/FFI:

  • CMake builds in common/src/commonMain/cpp/android/ and cpp/desktop/
  • Cross-compilation toolchains in cpp/toolchains/
  • Built libraries go to cpp/desktop/libs/ (organized by platform)

Configuration

local.properties (create from local.properties.example)

compression.level=0          # APK compression (0-9)
enable_debuggable=true       # Debug mode
application_id.suffix=.debug # Multiple app instances on same device
app.name=SimpleX Debug       # App name for debug builds

gradle.properties

Contains versions (Kotlin, Compose, AGP) and app version info. Key settings:

  • kotlin.jvm.target=11
  • database.backend=sqlite (or postgres)

Testing

Tests are in:

  • common/src/commonTest/kotlin/ - Cross-platform tests
  • common/src/desktopTest/kotlin/ - Desktop-specific tests (run with ./gradlew desktopTest)
  • android/src/androidTest/ - Android instrumented tests

Resources & Localization

  • String resources: common/src/commonMain/resources/MR/base/strings.xml + 21 language variants
  • Uses Moko Resources (dev.icerock.moko:resources) for cross-platform resource management
  • The adjustFormatting gradle task validates string resources during build

Platform-Specific Notes

Android

  • Min SDK 26, Target SDK 35
  • NDK 23.1.7779620
  • Supports ABI splits: arm64-v8a, armeabi-v7a
  • Deep linking requires SHA certificate fingerprint in assetlinks.json (see README.md)

Desktop

  • Distributions: DMG (macOS), MSI/EXE (Windows), DEB (Linux)
  • Mac signing/notarization configured via local.properties
  • Video playback uses VLCJ

Gotchas

In order for the SimpleX app to be automatically adopted for opening links from https://simplex.chat the SHA certificate fingerprint for the App installed on the phone must be in the hosted assetlinks.json file on simplex.chat.

The accepted fingerprints are in the sha256_cert_fingerprints list.

To find your SHA certificate fingerprint perform the following steps.

  1. Build and install your development version of the app as usual
  2. From the terminal in Android studio run adb shell pm get-app-links chat.simplex.app
  3. Copy the signature listed in signatures in the result
  4. Add your signature to assetlinks.json in the website repo and make a PR. On approval, wait a few minutes for the changes to propagate to the public website and then you should be able to verify SimpleX.

More information is available here. If there is no response when running the pm get-app-links command, the intents in AndroidManifest.xml are likely misspecified. A verification attempt can be triggered using adb shell pm verify-app-links --re-verify chat.simplex.app.

Note that this is not an issue for the app store build of the app as this is signed with our app store credentials and thus there is a stable signature over users. Developers do not have general access to these credentials for development and testing.

Adding icons

  1. Find a Material symbol in Rounded category.

  2. Set weight to 400, grade to -25 and size to 48px.

  3. Click on the icon, choose Android and download XML file.

  4. Update the color to black (#FF000000) and the size to "24.dp", as in other icons.

For example, this is add reaction icon.