Developing Mobile Apps with Kotlin Multiplatform Mobile (KMM)

Abstract

Kotlin Multiplatform Mobile (KMM) is a modern approach to cross-platform mobile app development, enabling developers to write shared assets that runs on both Android and iOS. This article delves into the core concepts, advantages, and practical aspects of using KMM for mobile app development. It also provides a comparison with other cross-platform frameworks and highlights real-world use cases, emphasizing the role of software development kit (SDK) in facilitating this process.

Introduction

The mobile app development landscape is continually evolving, with developers seeking efficient ways to deliver high-quality apps across multiple platforms. Kotlin Multiplatform Mobile (KMM) offers a compelling solution by allowing developers to write common code for Android and iOS, leveraging Kotlin’s expressive syntax and robust features. SDK(s) play a crucial role in this ecosystem, providing the necessary tools and libraries to streamline development. This article explores KMM’s capabilities, benefits, and how it compares to other cross-platform solutions.

Problem Statement

Developers often face challenges in maintaining separate codebases for Android and iOS apps, leading to increased development time, costs, and potential inconsistencies. KMM, supported by comprehensive SDK(s), addresses these issues by providing a shared codebase, reducing duplication of effort, and ensuring consistency across platforms.

 

                                                                                                                    

 Problem Overview (https://miro.medium.com/v2/resize:fit:720/format:webp/1*8Ne4eMYHJS2OZ4uYtv0QFw.png)

 

Detailed Content

Background and Context

Kotlin, a statically typed programming language developed by JetBrains, has gained popularity for its concise syntax, safety features, and full interoperability with Java. With the introduction of Kotlin Multiplatform, developers can now write shared code that runs on various platforms, including JVM, JavaScript, and native environments. KMM specifically targets mobile platforms, allowing for shared business logic while keeping platform-specific assets for user interface and other native features.

Core Concepts of Kotlin Multiplatform Mobile

1. Shared Code: KMM allows developers to write common assets for both Android and iOS, including business logic, data models, and network requests.

2. Expect/Actual Mechanism: Developers can write platform-specific implementations using the expect and actual keywords, facilitating seamless integration with native APIs.

3. Interoperability: KMM ensures smooth interoperability with existing codebases and libraries, enabling gradual adoption and integration into existing projects.

4. Modular Architecture: Projects can be organized into modules, with shared assets residing in a common module and platform-specific assets in separate modules.

KMM Architecture Diagram

Advantages of Kotlin Multiplatform Mobile

1. Code Reusability: By sharing code between Android and iOS, developers can significantly reduce duplication and streamline the development process.

2. Consistency: Shared business logic ensures consistent behavior across platforms, reducing the likelihood of platform-specific bugs and discrepancies.

3. Productivity: Kotlin’s expressive syntax, combined with the ability to share code, enhances developer productivity and accelerates the development cycle.

4. Flexibility: KMM allows for incremental adoption, enabling developers to gradually migrate existing projects or start new ones with a shared codebase.

5. Strong Community and Tooling: Backed by JetBrains and supported by a vibrant community, KMM benefits from robust tooling, comprehensive documentation, and active development.

Disadvantages of Kotlin Multiplatform Mobile

1. Learning Curve: Developers familiar with platform-specific development may face a learning curve when adopting KMM, particularly in understanding the expect/actual mechanism and handling platform-specific code.

2. Performance Overheads: While KMM aims for optimal performance, there may be some overheads associated with interoperation between shared and platform-specific code.

3. Maturity: As a relatively new technology, KMM is still evolving, and developers may encounter limitations or issues that require workarounds or additional effort.

Practical Comparison with Other Cross-Platform Frameworks

To illustrate how KMM compares with other cross-platform frameworks, let’s consider a simple example of making a network request and displaying the data in a mobile app.

Sharing different levels and UI (https://kotlinlang.org/docs/multiplatform.html#kotlin-multiplatform-use-cases)

Kotlin Multiplatform Mobile

In KMM, the shared code would handle the network request, and platform-specific code would manage the user interface.

Shared Code (Kotlin)

Kotlin Shared Example

Android Specific Code (Kotlin)

Android Specific Main Activity

iOS Specific Code (Swift)

 

iOS Specific View Controller

React Native

React Native uses JavaScript to write code that runs on both platforms, with native modules for platform-specific functionality.

Shared Code (JavaScript)

React Native Shared Example

Flutter

Flutter uses Dart to write apps that compile to native code for both platforms.

Shared Code (Dart)

Flutter Shared Example

Use Cases and Industry Applications

1. Enterprise Applications: KMM is well-suited for large-scale enterprise apps requiring consistent business logic across platforms.

2. E-commerce: Sharing code for business logic, data models, and network operations can expedite the development of feature-rich e-commerce apps.

3. Finance: Financial applications benefit from KMM’s ability to ensure consistency and reliability in critical business logic.

Case Studies or Examples

1. Netflix: Netflix adopted KMM to streamline the development of its Android and iOS apps, enabling faster feature development and ensuring consistency across platforms.

2. VMware: VMware uses KMM to develop its enterprise mobile apps, leveraging the shared codebase to maintain consistency and reduce development effort.

Conclusion

Kotlin Multiplatform Mobile offers a powerful solution for cross-platform mobile app development, enabling developers to write shared code that runs on both Android and iOS. By reducing duplication, enhancing consistency, and leveraging Kotlin’s robust features, KMM provides a compelling alternative to other cross-platform frameworks. Despite its learning curve and evolving nature, KMM holds great promise for efficient and maintainable mobile app development.

References

1. JetBrains. (2021). Kotlin Multiplatform Mobile. Retrieved from JetBrains KMM

2. Kotlin Multiplatform by Tutorials. Razeware LLC.

3. JetBrains. (2021). Kotlin Documentation. Retrieved from Kotlin Documentation