Kotlin Multiplatform KMP Case Study

Author: Karen Bonilla Author <KarenBonillaM>

Introduction

Kotlin, initiated by Jet Brains in 2010, is an open-source language designed for seamless interoperable with Java, capable of running on JVM (Java Virtual Machine). Boasting support for functional programming paradigms, Kotlin enhances code expressiveness with features like higher-order functions and lambdas.

Kotlin Multiplatform (KMP) extends the Kotlin language into cross-platform development. Developers share a unified codebase for business logic, written in Kotlin. The build process produces two native code libraries for Android and iOS. Platform-specific code is then implemented for the UI, consolidating shared business logic in one location.

Brief History

Kotlin Multiplatform (KMP) is an extension of the Kotlin programming language. The primary goal was to address the challenges of cross-platform development by enabling code sharing between different platforms.

2011: Kotlin language development announced.
2016: Official release in February.
2017: JetBrains introduced Kotlin Multiplatform as an experimental feature.
2017: Google adopts Kotlin as its official language for Android apps in May.
2017: KMP was introduced as an experimental feature in Kotlin 1.2, released in November.
Until 2020, the technology remained in the experimental stage.

Main Features

The primary purpose of Kotlin Multiplatform (KMP) is to streamline and enhance the process of cross-platform software development. It achieves this by enabling the creation of a shared codebase, primarily focusing on the business logic, which can be utilized across diverse platforms, including Android, iOS, and backend services. KMP’s technical architecture involves the generation of two native code libraries, one for Android and one for iOS, during the build process. Developers can then seamlessly integrate these libraries into their respective native projects, consolidating shared business logic while retaining platform-specific code for the user interface (UI).

In essence, KMP seeks to address the challenges associated with maintaining separate codebases for different platforms. By fostering code reusability and consistency, KMP enhances productivity, reduces development efforts, and provides a unified framework for creating high-performance applications across various operating systems. This technical approach aligns with the broader goal of efficient and resource-effective cross-platform development.

How KMP works

To enable common code functionality across platforms, Kotlin provides platform-specific compilers. For Android gets converted to Java bytecode, and executed in JVM. For iOS, the code is transformed into native code suitable for execution. The Frontend converts Kotlin code into the Intermediate Representation, which is then processed into machine-executable native code by the Backend.

Kotlin Multiplatform Advantages

Developing with Kotlin Multiplatform (KMP) offers several advantages:

Code Reusability: Write code once and deploy it across multiple device types.
Scaling with KMP. Efficiently add new functionalities to existing Android and iOS applications.
Code Sharing. Share a significant portion of their codebase across Android, iOS, and backend services, reducing duplication and ensuring code consistency.
Native Performance. Achieve performance akin to fully native apps by utilizing platform-specific UI components.
Consistent Language. Use Kotlin for both shared and platform-specific code, simplifying development and reducing the learning curve.
Productivity. Kotlin’s conciseness and expressiveness enhance productivity, with features like null safety and extension functions promoting cleaner code.
Interoperability. Seamless integration with Java (Android) and Swift (iOS), simplifying codebase integration and facilitating a smooth transition.
Typed Language. Kotlin’s static typing catches errors during compilation, improving code quality and reducing the chance of runtime bugs.
Cost Savings. Significant cost savings by sharing code across platforms, focusing on shared logic rather than maintaining a separate codebase.

Understanding and leveraging these technical features equips front-end developers with the tools needed to create high-performing and consistent applications across various platforms using Kotlin Multiplatform.

Kotlin Multiplatform Disadvantages

Complex Setup. Setting up Kotlin Multiplatform can be more intricate compared to frameworks like Flutter, requiring careful consideration of platform-specific requirements and dependencies.
Limited Support. Kotlin’s ecosystem, while growing, may not match the breadth of more established languages. Some platform-specific libraries may lack Kotlin Multiplatform support.
Platform-specific UI code. Despite shared business logic, developers need to implement the User Interface separately for each platform.
Compiled Code Size. The compiled code for Kotlin Multiplatform projects may be larger than equivalent platform-specific code, impacting application size.

Market Comparison

COMPARISON WITH FLUTTER

Performance Kotlin applications directly interacting with the devices, often run faster than the Flutter apps, which benefit from faster development and debugging with features like Hot Reload.

Learning Kotlin is considered an easy language, especially for Java developers. Flutter requires learning Dart for development.

Expendability Kotlin Multiplatform allows developers to create a common API for platform-specific functionalities, offering more flexibility than flutter.

Language Kotlin is more popular and loved according to the Stack Overflow Survey 2022, providing better compile-time safety.

Supported Platforms KMP was initially designed for Android and iOS, with evolving support for browsers and backends. Flutter targets a broader range of platforms using the same codebase.

Getting Started

Install Kotlin

Download and install one of these IDEs to start using Kotlin.

Creating a Kotlin Multiplatform project

Open your IDE:
Create a new project: Choose “File” -> “New” -> “Project”. Select “Kotlin” as the project type.
Configure project settings: Choose “Kotlin” as the platform. Enable the “Kotlin Multiplatform” option.
Define targets: Specify the platforms you want to target (e.g., JVM, Android, iOS).
Set up shared code: Create a shared module to contain code shared across platforms. Write your shared business logic, data models, etc., in this module.
Create platform-specific modules: For each platform (JVM, Android, iOS), create a module to contain platform-specific code. Implement UI-related code, API calls, etc., in these modules.

Conclusion

Kotlin Multiplatform (KMP) offers a powerful solution for cross-platform development, balancing code reusability, performance, and a consistent language experience. Understanding its advantages and limitations aids developers in making informed choices for their projects.

As the front-end landscape evolves, Kotlin Multiplatform stands out as a cost-effective solution, allowing developers to share code across platforms and focus on building and enhancing shared logic. This not only reduces development effort but also translates to significant cost savings.