Structure, Setup & Finest Practices

Key takeaways

• Kotlin Multiplatform Cell (KMM) lets you construct Android and iOS apps from a single codebase whereas retaining native UI efficiency.
• Share enterprise logic throughout platforms whereas retaining platform-specific UI and options.
• Preferrred for initiatives the place price, time-to-market, and consistency matter.
• Backed by JetBrains, robust neighborhood assist, and confirmed real-world adoption.

What’s Kotlin Multiplatform Cell (KMM)?

KMM is a framework that bridges the hole between native and cross-platform app growth, providing the efficiency of native with the effectivity of code sharing. The framework allows builders to:

• Write shared logic as soon as in Kotlin and run it on each Android and iOS.
• Maintain native UI layers for every platform, making certain platform familiarity.
• Scale back duplication, streamline updates, and enhance code maintainability.

Construction and structure

your-project/

├── shared/

│   ├── src/

│   │   ├── commonMain/

│   │   ├── androidMain/

│   │   └── iosMain/

├── androidApp/

└── iosApp/

Venture construction

A typical KMM venture consists of three predominant modules:

1. shared: Comprises the code that’s widespread between Android and iOS. This consists of enterprise logic, knowledge administration, and community requests.
2. androidApp: The Android-specific module the place the Android UI and platform-specific implementations reside.
3. iosApp: The iOS-specific module for iOS UI and platform-specific code.

Shared code

The shared module usually consists of the next:

• commonMain: Comprises the precise shared code throughout platforms.
• androidMain: Android-specific code.
• iosMain: iOS-specific code.

Structure

KMM helps widespread architectural patterns reminiscent of 

• MVVM (Mannequin-View-ViewModel) and 
• MVP (Mannequin-View-Presenter). 

The shared code handles the core logic, whereas the platform-specific modules handle the UI.

In style use circumstances for KMM

Create a Kotlin Multiplatform app with shared logic and native UI

One of many main Kotlin Multiplatform use circumstances is sharing code between cell platforms. You may share utility logic between iOS and Android apps and write platform-specific code solely when you must implement a local UI or work with platform APIs.

This sample works excellently for apps that need to really feel native whereas avoiding enterprise logic duplication. Music streaming providers usually take this route – sharing core playback logic, playlist administration, and advice methods whereas implementing platform-specific UI controls. This provides customers a well-known interface whereas sustaining constant performance beneath.

Create a Compose Multiplatform app with shared logic and UI

With the Compose Multiplatform UI framework, you may push the code-sharing capabilities of Kotlin Multiplatform past utility logic. You may implement the person interface as soon as after which use it for all of the platforms supported by Compose Multiplatform.

When companies want equivalent experiences throughout platforms, KMM shines by sharing each enterprise logic and person interface. Banking apps steadily use this method to make sure constant transaction flows and safety features. The unified expertise helps customers belief the applying, whereas builders profit from sustaining a single codebase for core performance.

Share a bit of logic

The applying will embody a module with shared code for each the iOS and Android platforms. The enterprise logic and knowledge entry layers might be applied solely as soon as within the shared module, whereas the UI of each purposes might be native.

Some purposes profit from sharing solely particular elements. E-commerce apps generally share cart administration and cost processing logic whereas retaining their UI and platform-specific options (like Apple Pay or Google Pay) native. This balanced method lets groups optimize for each code reuse and platform-specific capabilities.

At-a-glance: In style KMM use circumstances

Getting began with KMM

Set up the mandatory instruments

Examine your atmosphere

To ensure the whole lot works as anticipated, set up and run the KDoctor software:

1. KDoctor works on macOS solely. In case you use a unique working system, skip this step.
Within the Android Studio terminal or your command-line software, run the next command to put in the software utilizing Homebrew:

brew set up kdoctor

2. After the set up is accomplished, name KDoctor within the console:

kdoctor

3. If KDoctor diagnoses any issues whereas checking your atmosphere, assessment the output for points and potential options:

Repair any failed checks ([x]). Yow will discover drawback descriptions and potential options after the * image.

Examine the warnings ([!]) and profitable messages ([v]). They might include helpful notes and suggestions, as properly.

Why use Kotlin Multiplatform Cell (KMM)?

Advantages of KMM

Code reusability

Write as soon as and run on each Android and iOS, which considerably reduces growth effort and time.

Maintainability

Simpler to keep up and replace the shared logic as there’s just one codebase for each platforms.

Consistency

Ensures constant behaviour throughout each platforms through the use of shared enterprise logic.

Flexibility

Permits for platform-specific code and native UI, making certain that the app nonetheless feels native to the customers.

Neighborhood and assist

Sturdy neighborhood assist and in depth documentation make it simpler to get began and discover options.

Actual-world adoption tales

Many firms have efficiently adopted KMM:

Finest practices for KMM growth

• Begin small — migrate one function at a time.
• Maintain UI native for advanced platform-specific interactions.
• Use dependency injection for testability.
• Constantly take a look at on each platforms.
• Combine cell safety testing early (e.g., Appknox for compliance and privateness validation).

Remaining thought

Kotlin Multiplatform Cell is a practical center floor between full native and absolutely cross-platform growth, providing a robust strategy to streamline app growth for Android and iOS. 

By sharing code between platforms, builders can scale back growth time, guarantee consistency, and keep flexibility for native experiences. It reduces engineering overhead with out compromising on efficiency or person expertise, making it a robust selection for each startups and enterprises.

So, whether or not you are beginning a brand new venture or seeking to optimize your current workflow, KMM gives a compelling resolution for contemporary cell growth.

Regularly requested questions (FAQs)

1. Is Kotlin Multiplatform Cell secure for manufacturing?

Sure. Kotlin Multiplatform Cell has reached a degree of maturity the place it’s utilized in manufacturing by main manufacturers like McDonald’s, VMware, Philips, and Money App. Its stability comes from JetBrains’ energetic growth and a sturdy launch cycle, making certain compatibility with the newest Android and iOS SDKs. 

Whereas sure UI-related options (like Compose for iOS) are nonetheless evolving, the shared logic layer is production-ready and confirmed at scale.

2. How a lot code could be shared?

Usually, 60–90% of your utility’s code could be shared between Android and iOS, together with 

• Enterprise logic, 
• Knowledge fashions, 
• Community calls, and 
• Utility capabilities. 

The remaining proportion often entails platform-specific UI and integrations — reminiscent of push notifications, cost gateways, or OS-level APIs — which are finest applied natively.

3. How does KMM differ from Flutter or React Native?

KMM focuses on sharing core enterprise logic whereas leaving the UI layer absolutely native for every platform, which means your app seems and behaves precisely like different native apps. 

Flutter and React Native, alternatively, render their very own UI elements, changing the native UI layer totally. 

This implies KMM preserves platform-specific UX and efficiency advantages, whereas Flutter/React Native intention for a single cross-platform UI expertise.

4. Does KMM assist Compose for iOS?

Sure. KMM helps Compose for iOS by Compose Multiplatform, which helps you to construct a shared UI layer for Android and iOS utilizing the identical code. 

Nevertheless, the iOS aspect continues to be comparatively younger in comparison with Android, so groups ought to consider efficiency and have completeness earlier than committing. It’s a superb possibility for initiatives that want equivalent UI throughout platforms with out sustaining two separate UI codebases.

5. Can I migrate an current native app to KMM?

Sure, completely. 

Migration could be incremental, which implies you don’t have to rebuild your whole app from scratch. 

You can begin by shifting remoted options or enterprise logic — like authentication, API calls, or knowledge dealing with — into the shared module, whereas retaining your current native UI intact. This method reduces danger and permits for gradual adoption.

6. What about app safety with KMM?

Despite the fact that KMM centralizes your corporation logic, that shared code nonetheless wants thorough safety testing. Vulnerabilities within the shared module can impression each Android and iOS apps concurrently. 

Integrating instruments like Appknox ensures steady scanning for safety flaws, privateness violations, and compliance dangers, protecting each the shared logic and platform-specific layers.