공유 코드에서 UI 제외하기

Shared code holds logic; the UI stays native. Drawing this line early keeps your common module portable to every target.

Android views and SwiftUI are platform-specific. Putting them in commonMain would break compilation on the other target instantly.

Calculations, rules and models are what truly repeat across apps. That logic is the high-value code worth sharing once.

Shared functions should hand back plain data, like a total or a label string, never a button or a view.

Showing a message is a UI job. Shared code returns the text to show; each app decides how to display it.

Hex colors and fonts are presentation. Keep styling in each platform's UI so designers can tune apps independently.

Shared code can publish state the UI watches. The apps render it however they like, but never the other way around.

UI depends on shared code, never the reverse. This one-way arrow is what keeps the common module clean and reusable.

Compose Multiplatform can share UI too, but it is opt-in. Your core logic module still stays UI-free and lightweight.

If a shared file imports a platform UI package, that is a smell. Move that code out into the right app module.

A UI-free shared layer compiles everywhere and adds new targets with ease. Discipline here is what makes KMP pay off. 🚀

What should a shared function return instead of a UI widget?

You kept widgets, colors and alerts out of common code and let it expose only data the native UIs render. ✅