Kotlin Multiplatform Mobile Development: Guide 2026

Kotlin Multiplatform Mobile: Shared Logic, Native UI

Kotlin multiplatform mobile enables sharing business logic, networking, and data layers between Android and iOS while keeping native UI on each platform. Therefore, teams maintain the native look and feel users expect while eliminating duplicate business logic implementation. As a result, development velocity increases without sacrificing platform-specific user experiences.

KMP Architecture Overview

The shared module contains platform-agnostic code including data models, repository patterns, and business rules. Moreover, expect/actual declarations provide a mechanism for platform-specific implementations within the shared codebase. Consequently, code sharing ratios of 60-80% are achievable without compromising native capabilities.

Compose Multiplatform extends the sharing opportunity to the UI layer for teams comfortable with declarative UI across platforms. Furthermore, the shared module can integrate with Swift Package Manager on iOS for seamless dependency management.

Kotlin Multiplatform Mobile Data Layer

SQLDelight provides cross-platform database access with type-safe SQL queries that compile to native code on each platform. Additionally, Ktor client handles networking with platform-specific HTTP engines for optimal performance. For example, OkHttp on Android and URLSession on iOS provide the best networking experience on each platform.

// Shared data layer with SQLDelight + Ktor
class ProductRepository(
    private val database: AppDatabase,
    private val api: ProductApi
) {
    suspend fun getProducts(): Flow<List<Product>> {
        // Fetch from API and cache in local database
        try {
            val remote = api.fetchProducts()
            database.productQueries.transaction {
                remote.forEach { product ->
                    database.productQueries.insertOrReplace(
                        id = product.id,
                        name = product.name,
                        price = product.price,
                        category = product.category,
                        updatedAt = Clock.System.now().toEpochMilliseconds()
                    )
                }
            }
        } catch (e: Exception) {
            println("Network error, using cached data: " + e.message)
        }
        // Return reactive flow from local database
        return database.productQueries.selectAll()
            .asFlow()
            .mapToList(Dispatchers.Default)
    }
}

The repository pattern abstracts data sources so consuming code never deals with API calls or database queries directly. Therefore, the same business logic works identically on both platforms.

iOS Integration Best Practices

Integrating KMP with SwiftUI requires careful attention to Kotlin/Native memory management and coroutine bridging. However, libraries like SKIE generate Swift-friendly APIs that make Kotlin code feel natural in Swift. In contrast to React Native or Flutter, KMP does not replace the native UI layer, avoiding platform abstraction issues.

Testing Shared Code

Shared module tests run on both JVM and native targets to verify platform-independent behavior. Additionally, expect/actual test utilities handle platform-specific test setup like database drivers and HTTP mock servers. Specifically, the commonTest source set ensures business logic tests execute across all target platforms.

Related Reading:

• Flutter WASM Web Performance
• iOS SwiftUI Navigation
• Jetpack Compose Performance

Further Resources:

• Kotlin Multiplatform Docs
• Android KMP Guide

In conclusion, Kotlin multiplatform mobile development offers the best balance between code sharing and native platform fidelity. Therefore, adopt KMP to eliminate duplicated business logic while preserving the native user experience your users expect.