kmp-spm

A demo Kotlin Multiplatform + Compose Multiplatform project that runs on Android, iOS (via Swift Package Manager), and Web (Wasm/JS).

Layout

.
├── composeApp/                       # KMP module — Android app + iOS framework + Wasm web
│   └── src/
│       ├── commonMain/               # Shared Compose UI + business logic
│       ├── androidMain/              # Android entry point (MainActivity)
│       ├── iosMain/                  # ComposeUIViewController bridge for iOS
│       └── wasmJsMain/               # Wasm/JS entry point + index.html
├── iosApp/iosApp/                    # SwiftUI shell that hosts the Compose view
├── Package.swift                     # Local SPM package wrapping the XCFramework
└── gradle/, settings.gradle.kts, …   # Standard Gradle scaffolding

The iOS app does not depend on the Gradle/Kotlin output directly. Instead:

1. Gradle builds composeApp/build/XCFrameworks/release/Shared.xcframework.
2. The root Package.swift exposes that XCFramework as a Swift Package called Shared.
3. Xcode pulls in the SPM package as a local dependency.

One-time bootstrap

1. Build the iOS XCFramework

./gradlew :composeApp:assembleSharedReleaseXCFramework
# or for faster iterative dev:
./gradlew :composeApp:assembleSharedDebugXCFramework

This produces composeApp/build/XCFrameworks/release/Shared.xcframework (or debug/). If you use the debug variant, edit Package.swift to point at debug/ instead.

The Gradle wrapper is checked in, so the first run will download Gradle 8.10.2 automatically — no system-wide gradle install needed.

2. Create the iOS Xcode project

The Swift sources live at iosApp/iosApp/, but the .xcodeproj isn't generated yet.

In Xcode:

1. File ▸ New ▸ Project ▸ iOS App — name it iosApp, save inside iosApp/, replacing the existing folder if asked. (Or save elsewhere and move the two .swift files in.)
2. Delete Xcode's generated ContentView.swift and iosAppApp.swift; add the two files already in iosApp/iosApp/ instead.
3. File ▸ Add Package Dependencies… ▸ Add Local… — select the repo root (/Users/brian/Dev/kmp-spm). Add the Shared product to the iosApp target.
4. Build & run on a simulator.

If the Shared import fails to resolve, make sure step 1 (assembleShared…XCFramework) ran first — SPM resolves the binary target by reading the file on disk.

Running each platform

Platform	Command
Android	./gradlew :composeApp:installDebug (or run from Android Studio)
iOS	Build & run iosApp from Xcode
Web (Wasm)	./gradlew :composeApp:wasmJsBrowserDevelopmentRun then open the printed URL

Tweaking versions

All versions live in gradle/libs.versions.toml. Bumping Kotlin, AGP, or Compose Multiplatform from a single place reduces compatibility surprises.

Known sharp edges

• XCFramework path in Package.swift is hardcoded to release/. Switch to debug/ for dev iteration (smaller, faster builds), but remember to rebuild whenever shared Kotlin code changes — SPM caches binary targets aggressively.
• Compose iOS framework size: a hello-world XCFramework is ~40–60 MB in debug. Release ARM64-only is much smaller.
• Configuration cache is on. If a plugin misbehaves, disable temporarily with --no-configuration-cache.