This isn't about forcing a square peg into a round hole. It’s about strategically sharing the most expensive, complex, and bug-prone part of your application: the core business logic.

In mobile development, we face 3 fundamental, profit-eroding problems that KMP is designed to solve. They all directly impact your financial statements:  

1. The Cost of Duplication

Say you’ve hired two separate architects to design the foundation of your new corporate headquarters. They both receive the same blueprints for the electrical, plumbing, and security systems, but they are required to draw them in two different languages.  

That is the current state of native mobile development.

Every time a product manager asks for a new feature—a complex pricing algorithm, a new data validation rule, or a secure payment flow—your company pays for it twice.  

Once for the Android team to write it in Kotlin, and again for the iOS team to write it in Swift.

This isn't just about developer salaries; it’s about the hidden costs of maintaining two separate sets of unit tests, two separate bug reports, and two separate code review cycles for the exact same business rule.

KMP (Kotlin Multiplatform) allows you to consolidate that core logic—the data models, the networking stack, the payment processing rules—into a single, shared module.  

Think of it as a single, centralized "brain" for your application. This brain is written in Kotlin, and it can speak fluently to both the Android and iOS platforms. You are no longer paying for two implementations; you are paying for one implementation and two thin communication layers. The reduction in long-term maintenance debt and the elimination of redundant work is, frankly, staggering.

2. The Feature Parity Headache

The "Android has it, iOS is two weeks behind" syndrome is a silent killer of user experience and brand consistency.  

It forces marketing teams to segment campaigns and creates friction for users who switch devices. It makes your brand look inconsistent and disorganized.

KMP ensures that the core behaviour of your application is identical on both platforms because it is literally the same code.  

When you fix a bug in the shared Kotlin module, you fix it simultaneously for both Android and iOS. This is a guarantee of shared business logic mobile apps that ensures a consistent, high-quality user experience across all devices.  

Your product team can finally focus on what to build, not where to build it first.

3. Leveraging Your Talent Investment

KMP is not a new language or a new framework to learn from scratch. It is an extension of Kotlin.

This means that Android developers can immediately contribute to the iOS side of the project by writing shared logic. You are not hiring expensive, specialized cross-platform developers; you are simply making your existing talent pool more effective.  

It’s a strategic move that maximises the return on your talent investment and makes your hiring process easier, as high-quality Kotlin developers can be easier to find than developers who are equally expert in both Swift and Kotlin.  

Of course, a mobile app development agency like ours can provide both if that’s what you’d prefer.

For the CTO who needs to understand the mechanics, and for the business leader who needs to understand the guarantees, let’s talk about how this works under the hood.  

This is where KMP distinguishes itself from other cross-platform solutions like Flutter or React Native.

Kotlin Multiplatform (KMP)

• What is Shared? - The "brain" (business logic, data, networking)

• User Interface - Built with native tools (SwiftUI/UIKit)

• Performance - Near-native (logic)

• Risk Profile - Low (logic is portable)

Flutter / React Native

• What is Shared? - The "skin" (UI and logic)

• User Interface - Built with a third-party framework

• Performance - Good (via a rendering engine)

• Risk Profile - Medium (All-in on a single framework)

Native (Swift/Kotlin)

• What is Shared? - Nothing

• User Interface - Built with native tools

• Performance - Best

• Risk Profile - Low (platform-specific)

The key takeaway for a business leader worried about whether Kotlin can be used for iOS is this: KMP allows your iOS team to continue building the UI using the native tools they know and love (SwiftUI), ensuring a perfect, platform-specific user experience.  

The shared Kotlin code simply provides the high-performance, consistent engine that powers the app.

The shared Kotlin code is compiled into a native framework that can be imported directly into an Xcode project.  

For a long time, the shared code would "speak" to Swift with a heavy, confusing accent. This is where the industry has matured, and you need to be aware of the solution: SKIE (Swift Kotlin Interop Enhancement).

SKIE is a tool that acts as a sophisticated translator. It ensures that the shared Kotlin code presents itself to the Swift team in a clean, modern, and idiomatic way.  

This is a crucial detail. It means your iOS developers can consume the shared logic using modern Swift features, making the integration feel seamless.  

The Performance Question

For the executive worried about performance, the answer is simple: Kotlin for iOS performance is not a concern for 99% of business applications.  

Since KMP compiles to native code, the performance of the shared logic is near-native. The UI, which is the part of the app most sensitive to performance, is still rendered using native technologies. You get the efficiency of shared code without the performance penalty of traditional cross-platform solutions.

One of the most compelling arguments for KMP is its non-disruptive, incremental adoption model. Unlike other cross-platform solutions that demand a full rewrite, KMP is designed to be integrated piece by piece.  

This is the answer to the question: "Can Kotlin be used for iOS with our existing codebase?"

The strategy is simple, minimises risk, and maximises value at every step:

Phase 1: The Foundation

Start by sharing the simplest, most stable part of your application: the data layer.  

This includes the definitions of your data (the models) and how the app talks to your servers (the networking).

This is a low-risk, high-reward move. It immediately eliminates the chance of data parsing errors or model inconsistencies between platforms. If, for some reason, the experiment fails, you simply remove the KMP module, and your native codebases are untouched. You have a built-in, low-cost exit strategy.

Phase 2: The Engine

Once the foundation is stable, move to the complex business logic: the rules for how data is processed, validated, and stored.  

This is where the majority of your development cost is saved and where the risk of platform-specific bugs is eliminated. By centralizing this logic, you guarantee that your Android and iOS apps behave identically, achieving true feature parity.

Phase 3: The Polish

With the advent of Compose Multiplatform iOS stability, you now have the option to share the UI as well. However, for most enterprises, the best strategy remains: Shared Logic, Native UI.  

Your iOS team is best equipped to deliver a truly native, polished user experience using Swift and SwiftUI, while your Kotlin team provides the robust, shared engine underneath. Only consider shared UI if your application has a highly custom, non-native look and feel that must be identical across platforms (e.g., a game or a highly branded utility).

The decision to adopt Kotlin Multiplatform is a strategic one, not a technical one. It is a decision to shift your development focus from duplication to consolidation.

If you are a business owner or CTO, here is decision framework for different scenarios:

You have an existing, mature Android app in Kotlin.

Adopt KMP incrementally: You leverage your existing Kotlin investment. Starting with the data layer is a low-cost experiment that immediately cuts maintenance and guarantees data consistency.

You are starting a new project

KMP is the default choice: Build the core logic once from day one. This is the most efficient path to market for a dual-platform app, saving significant development budget.

Your iOS team is highly resistant to any change.

Focus on the SKIE factor: KMP with SKIE delivers a clean, idiomatic Swift framework. Your iOS team can focus on what they do best—native UI/UX—and stop wasting time rewriting logic.

Your primary concern is a highly custom, pixel-perfect UI.

Use KMP for logic, Native for UI: KMP provides the robust, shared engine, while your native teams use SwiftUI/UIKit to deliver the best possible platform-specific user experience. You get the best of both worlds.

Kotlin Multiplatform is not a silver bullet that eliminates the need for iOS developers. It is a sophisticated tool that allows your iOS developers to stop writing redundant business logic and start focusing on delivering the best possible native experience. It transforms your Android team from a platform-specific asset into a core-logic powerhouse.

The time for skepticism is over. The technology is stable, the tooling is mature, and the business case is undeniable. The question is no longer if Kotlin for iOS is possible, but when you will start capitalizing on the efficiency it offers.  

The future of mobile development is not about writing code once; it’s about writing the right code once. And this is where the developers at Octogle can advise you (for free!). Connect with us today.