Compose Multiplatform: Sharing UI Across Android, iOS, and Desktop

From Sharing Logic to Sharing UI

Kotlin Multiplatform started as a way to share business logic while keeping native UIs. Compose Multiplatform (from JetBrains) pushes further: the same Compose UI code that runs on Android now renders on iOS, desktop, and web too, via Skia.

How it actually renders

On Android, Compose Multiplatform is just Jetpack Compose — no difference. On iOS and desktop, it renders through Skia (the same 2D graphics engine Flutter uses), producing pixel-identical UI across platforms rather than translating to native UIKit components.

@Composable
fun App() {
    MaterialTheme {
        var count by remember { mutableStateOf(0) }
        Column(modifier = Modifier.padding(16.dp)) {
            Text("Count: $count")
            Button(onClick = { count++ }) { Text("Increment") }
        }
    }
}

That exact function runs unmodified on Android, iOS, and desktop targets.

Where this makes sense

• Internal tools and dashboards — visual consistency matters more than platform-native feel.
• Teams already invested in Compose — your Android devs' skills transfer directly instead of learning SwiftUI or Dart.
• Design-system-heavy products — if your app already overrides Material defaults heavily, you're not losing much "native feel" you didn't already customize away.

Where it's still rough

• iOS interop — calling into UIKit-based libraries (camera SDKs, ad networks, some payment SDKs) requires bridging code, similar to Flutter's platform channels.
• Platform look and feel — you get iOS-appropriate widgets only if you explicitly theme for it; the defaults skew Material.
• Maturity — it's stable for production but younger than Flutter; expect to hit rougher edges in text rendering, accessibility, and some layout edge cases.

KMP vs Compose Multiplatform — not the same decision

You can adopt "vanilla" KMP (shared logic, native SwiftUI/Compose UI per platform) without ever touching Compose Multiplatform. The two are independent choices:

If your product's iOS users would notice — and complain — that the app doesn't feel like iOS, stick to native UI with shared KMP logic. If a consistent cross-platform identity is more valuable than platform-native polish, Compose Multiplatform is worth a serious pilot.