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Returning the platform name is the classic first expect/actual you write. It proves your shared module really runs on both apps. 👋

Start in commonMain with an expect function that returns a String. No body yet, just the shape both platforms agree on.

In androidMain, provide the actual using Android's Build class to report the Android version at runtime.

In iosMain, the actual reaches into Apple's UIKit to read the device's system name and version.

Both actuals share the exact name, parameters, and return type of the expect. One mismatch and the compiler refuses to build.

Now any common function can call platform() freely. It reads like normal Kotlin while the right actual runs underneath.

When the Android app calls greeting(), the compiler linked the androidMain body, so it shows the Android string.

The very same call from Swift returns the iOS version instead, because the iosMain actual was compiled into that framework.

Notice that Build and UIDevice are imported only in their own source sets. Shared code never imports a platform type directly.

Keep the expect small and focused. One function that returns a name is enough to bridge into each platform cleanly. ✨

Run both apps and print the result. Seeing two different strings confirms your expect/actual wiring works end to end.

Think about how the right value gets chosen.

You built the classic platform() function: one expect in commonMain, an actual in androidMain and iosMain, and matching signatures across all three. 🎉