FOSDEM 2026 Swift Talk

Intro

• Marc Prud’hommeaux (marc@skip.dev)
• Founding member of Swift Android workgroup
• iOS & Android Developer since 2008
• Creator of Skip (skip.dev né skip.tools)
• Slides: skip.dev/talks/fosdem2026 ↗

Flash Poll: Audience Swift Focus

• iOS
• macOS
• Server
• Embedded
• Windows
• WebAssembly
• Android
• Other

Android

• Most widely-used operating system in the world
• ~4 billion Android handset device users
• OS for myriad of IoT/embedded/auto devices
• Linux Kernel (GPL)
• Android Open Source Project (AOSP) (Apache)
• Android Certified (proprietary)
  • Google Mobile Services + Google Play Services

Android for iOS Developers: Development

	iOS	Android
Modern Language	Swift	Kotlin
Legacy Language	Objective-C	Java
Build System	SwiftPM	Gradle
Platform SDK	Obj-C (+C & Swift)	Java (+C)
OS/Kernel	XNU/Darwin	non-GNU/Linux
Native Libraries	Mach-O .dylib	ELF .so

Android for iOS Developers: App Development

	iOS	Android
IDE	Xcode	Android Studio, IntelliJ, …
Virtual Device	iOS Simulator	Android Emulator
UI Framework	SwiftUI (Swift)	Jetpack Compose (Kotlin)
UI (Legacy)	UIKit (Obj-C)	XML Views (Java)
App Packaging	.ipa	.apk
Distribution Portal	App Store Connect	Google Play Console
App Marketplace	Apple App Store	Google Play Store

A Brief History of Swift on Android

See Native Swift on Android, Part 1, September 2024 ↗

• Running Swift code on Android ↗, Romain Goyet, October 14, 2015
• How we put an app in the Android Play Store using Swift ↗, Geordie J, Jul 8, 2016
• Android Community Workgroup formed February 2025 ↗
• Android Workgroup officially formed June 2025 ↗

Contributor Hall of Fame

• andriydruk* ↗
• compnerd* ↗
• finagolfin* ↗
• ephemer ↗
• hyp ↗
• mstokercricut ↗
• vgorloff ↗

How Does it all Work?

Flash Poll 2: Swift Cross-Compilation SDK Experience

• Static Linux (musl)
• Webassembly (wasm)
• Android

Swift Cross-Compilation SDK

• SE-0387: Swift SDKs for Cross-Compilation ↗ implemented in Swift 6.1 (2024)
• Self-contained .artifactbundle archive
• Enables building for a separate target than the host
• e.g., build for Android from macOS or Linux
• Like building for iOS from macOS
• Other Swift SDKs: WebAssembly (wasm), Static Linux (musl)

Structure of the Swift SDK for Android

Unlike the other Swift SDKs, the Swift SDK for Android is not self-contained. It requires an external “Native Development Kit”

1. Host Toolchain (OSS via swiftly, not Xcode)
2. Swift SDK for Android
3. Android Native Development Kit (NDK)

Structure of the Swift SDK for Android: 1. The Host Toolchain

• Host Toolchain (OSS via swiftly, not Xcode)
  • Lives in:
    • ~/Library/Developer/Toolchains/swift-6.2.3-RELEASE.xctoolchain/
  • (NOT: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain)
  • Provides: swiftc

Structure of the Swift SDK for Android: 2. The Swift SDK for Android

• Swift SDK for Android
  • Lives in: ~/Library/org.swift.swiftpm/swift-sdks/swift-6.2.3-RELEASE_android.artifactbundle/

Structure of the Swift SDK for Android: 3. The Android Native Development Kit (NDK)

• Android Native Development Kit (NDK)
  • Lives somewhere like:
    • ~/Library/Android/sdk/ndk/27.0.12077973/
  • Provides:
    • aarch64-linux-android28-clang, x86_64-linux-android35-clang, ld
  • Outputs: lib/arm64-v8a/libMySwiftCode.so

Setup

• Getting Started with the Swift SDK for Android — swift.org ↗
• NDK not included
• Install an emulator for testing

Building

• Build for ARM (64):

swift build --swift-sdk aarch64-unknown-linux-android28

• Build for X86 (64):

swift build --swift-sdk x86_64-unknown-linux-android28

Android Architectures

• arm64-v8a (64-bit ARM): handsets, most popular
• armeabi-v7a (32-bit ARM): older handsets, IoT
• x86_64 (64-bit Intel): Chromebooks, dev emulators
• x86 (32-bit Intel)
• mips (old RISC)
• riscv (new RISC)

What Works, What Doesn’t

The Swift SDK for Android comes with a number of built-in .swiftmodules

Available Frameworks

• Swift standard library
• Foundation
• Dispatch
• Observation
• Testing & XCTest
• Android (instead of Darwin)

Unavailable Frameworks

Pretty much everything else…

• CoreGraphics, CoreLocation, etc.

• CloudKit, StoreKit, GameKit, HealthKit, etc.

• UIKit, SwiftUI

• Rule of thumb: if it isn’t available on Linux, then it won’t be available on Android.

Third-party Packages

• swiftpackageindex.com: search “platform:android”
• Adding Android compatibility testing ↗ blog post
• ~30% of their ~9k packages build for Android
  • swift-collections, swift-crypto, swift-log, …
  • Alamofire, Factory, Yams, GraphQL, Supabase, …

Porting

How can we get our own Swift Packages working on Android?

• Porting Swift Packages to Android – skip.dev/docs/porting/ ↗
• iOS ➜ macOS ➜ Linux ➜ Android

Porting Example

#if canImport(Darwin)
import Darwin // macOS, iOS, etc.
#elseif canImport(Glibc)
import Glibc // for Linux
#elseif canImport(Android)
import Android // or Bionic
#endif

import Foundation
// non-Darwin Foundation doesn't include FoundationNetworking
#if canImport(FoundationNetworking)
import FoundationNetworking
#endif

Running an Executable

swift package init --name DemoCmd --type executable
swift run DemoCmd # builds and runs on host

swiftly run swift build --swift-sdk aarch64-unknown-linux-android28 --static-swift-stdlib

adb push .build/aarch64-unknown-linux-android28/debug/DemoCmd /data/local/tmp/
adb push …/libc++_shared.so /data/local/tmp/

adb shell /data/local/tmp/DemoCmd

https://www.swift.org/documentation/articles/swift-sdk-for-android-getting-started.html ↗

Testing a Library

• Local Testing

swift package init --type library --name DroidLib
swift test
skip android test

• Continuous Integration
  • Swift Android Action (Linux or macOS)
  • https://github.com/marketplace/actions/swift-android-action ↗

Current Status of Swift SDK for Android

• Available as 6.3 and main branch nightly snapshots

• Will be part of Swift 6.3 release (Spring 2026)

• WIP: Debugging ↗

• WIP: Testing Improvements ↗

• WIP: IDE Support

• TODO: Packaging ↗, Integration (Gradle, etc.)

• TODO: Size Reduction ↗: thinning ICU?

Next Up: Java Integration

• CLIs and tests aren’t an app
• Android apps need to work with the Android SDK…
  • …which is Java
  • …and that means the Java Native Interface (JNI)
• Mads is up next to talk about that…

How you can help

• Try it out, give feedback
  • https://forums.swift.org/c/platform/android ↗
• Add Android support to your packages
  • add Android to your CI matrix

Thank You!

• Marc Prud’hommeaux (marc@skip.dev)
• FODEM: find me at the F-Droid kiosk (UD1)
• Slides: skip.dev/talks/fosdem2026 ↗