Comprehensive Guide to Kotlin/Native for Cross-Platform Development

Introduction to Kotlin/Native for Cross-Platform Development

Kotlin/Native is an exciting part of the Kotlin ecosystem that allows Kotlin code to run on platforms outside the Java Virtual Machine (JVM). By compiling Kotlin into native binaries,

Kotlin/Native extends the reach of Kotlin to systems like iOS, macOS, Linux, Windows, and even embedded devices. This opens up vast opportunities for Kotlin developers to build applications that run natively on a variety of platforms, from mobile to desktop and IoT devices, without needing a JVM.

In this article, we’ll explore what Kotlin/Native is, how it works, its key features, and the scenarios where it shines the most. We’ll also discuss its importance within Kotlin’s broader Multiplatform project, which is designed to help developers write reusable code across multiple platforms.

What is Kotlin/Native?

At its core, Kotlin/Native is a compiler technology that allows Kotlin code to be compiled to native binaries for various platforms. This means Kotlin code can be executed directly on a device without relying on a virtual machine (like the JVM) or additional runtime layers.

Kotlin/Native leverages LLVM (Low-Level Virtual Machine), a powerful compiler infrastructure, to generate highly optimized binaries that can run on platforms such as:

• iOS
• macOS
• Linux
• Windows
• Embedded systems (e.g., ARM architectures)
• WebAssembly (Wasm)

Why Kotlin/Native?

Kotlin was originally designed primarily as a language for the JVM. While this means that Kotlin developers can use Kotlin transparently with Java code and can benefit from the JVM’s features, it strictly limits the number of platforms on which Kotlin can run. This eliminates a huge limitation: Kotlin/Native compiles Kotlin code to native executables, loosening the constraints on language usage, expanding the use of the language on a very specific range of applications, particularly on platforms where there is no JVM, for example, iOS or on embedded devices.

This was a possibility which placed Kotlin/Native as the key part of an initiative: Kotlin Multiplatform. This will make Kotlin truly cross-platform such that code can be shared among mobile, desktop, server, and web applications.

How Kotlin/Native Works

Kotlin/Native turns Kotlin source code into native machine code. Let’s break down the steps:

• Source Code in Kotlin: You write your code as you would for any JVM-targeting Kotlin application.
• Kotlin/Native Compiler: Kotlin/Native compiler takes this source code and, unlike giving away to the JVM to produce the corresponding bytecode, the compiler turns the code into some form of intermediate representation using LLVM.
• LLVM Target Toolchain: LLVM may perform optimizations and translate the IR to platform-specific machine code. The latter is then executed on a target operating system or hardware.
• Native Binary: This is the final output. It is a platform-specific native binary that can be run natively on chosen environments like an iOS device, a Linux server, or a Windows machine.

Unlike Kotlin for JVM, Kotlin/Native does not necessitate the presence of any virtual machine or runtime environment to execute the code. This makes Kotlin/Native ideally suited for situations where memory constraints or performance requirements make the usage of a full-fledged virtual machine impossible.

Key Features of Kotlin/Native

1. No JVM Dependency

Maybe, one of the fundamental advantages that can be cited about Kotlin/Native is no dependency upon a JVM. This particular aspect leads to its use in scenarios where JVM is not supported or else is not practical at all: iOS, for example, or embedded devices.

2. Interop with C and Objective-C

Kotlin/Native has very good interoperability with both C and Objective-C code. That is, one may call existing C libraries and even interact with platform-native APIs on platforms like macOS and iOS. Kotlin/Native also generates header files for calling Kotlin code from C.
For example, on iOS, Kotlin/Native enables integration directly with Apple’s native frameworks like UIKit or Core Data. Therefore, it is a pretty good choice when performing cross-platform mobile development.

3. Multithreading and Concurrency

Kotlin/Native has a particular concurrency model built around coroutines and frozen objects. On the other hand, Kotlin on JVM leans back on the JVM’s garbage collection and threading model. In the former case, it uses reference counting. It shares objects differently between threads.

In Kotlin/Native, one needs to “freeze” an object before one can share it between threads. This protects any modifying access after an object has been shared to ensure safe concurrency.

4. Memory Management

Kotlin/Native is done on automatic memory management. However, it instead relies on reference counting and deferred free of resources rather than on the garbage collector implemented in the JVM. This approach is closer to the treatment of memory in Swift or Objective-C, so Kotlin/Native comes out good, specially for iOS development.

5. Multiplatform Support

Kotlin/Native is the base of Kotlin Multiplatform, which means that developers can share code and write one program to run an application on multiple platforms: from Android and iOS up to JVM and JS, holding separate modules for platform-specific code. It ensures quite efficient reuse of code in business logic, networking, and data manipulation.

6. Support WebAssembly

Kotlin/Native targets WebAssembly, too; it means the code written in Kotlin can run within current browsers. It is pretty interesting for developing high-performance web applications, making Kotlin a versatile language for all-round development.

When to Use Kotlin/Native

Kotlin/Native is particularly useful in the following scenarios:

1. iOS Development

In cross-platform mobile development, Kotlin/Native is heavily adopted. Now you can write shared business logic that works in Android (Kotlin/JVM) and iOS (Kotlin/Native). Without code duplication, teams can develop one codebase that works on both platforms yet still takes advantage of native UI frameworks – SwiftUI for iOS, and Jetpack Compose for Android.

2. Cross-Platform Apps

They use Kotlin/Native in combination with Kotlin Multiplatform. So, you can develop desktop applications and aim for Windows, macOS, and Linux. You can even write command-line tools. It means that developers needn’t keep track of multiple codebases for multiple platforms.

3. Embedded Systems and IoT

Target Embedded systems, such as ARM architectures. It is the best fit in case you require to build applications which would run on resource-constrained devices. IoT devices, microcontrollers, or something alike. Write safer and more maintainable code for your embedded environments using Kotlin’s modern syntax.

4. Web Development with WebAssembly

That can go as far as to make the opportunity for building client-side web applications using Kotlin, real better performance and cross-platform capabilities, appear.

5. Command-Line Tools

could be Kotlin/Native used to create command-line applications, lightweight that run natively without VM overhead, that could easily be used to write small utilities or system scripts.

Kotlin/Native and Kotlin Multiplatform

Kotlin/Native is another integral part of the Kotlin Multiplatform project, and allows business logic to be shareable between platforms in such a way that you only write it once, but reuse it everywhere-you could put shared code across different platforms, including Android, iOS, desktop, and even web.

For example, you can have one shared module responsible for network requests, business logic, or data storage and then target iOS and Android separately with native UI development using Swift and Jetpack Compose respectively.

Getting Started with Kotlin/Native

To begin with Kotlin/Native, you have to download a release of IntelliJ IDEA that supports the Kotlin plugin and configure your Gradle build file as follows for Multiplatform development. Below is a minimal setup in which you want to target macOS and iOS:

plugins {
    kotlin("multiplatform") version "1.6.0"
}

kotlin {
    ios {
        binaries {
            framework {
                baseName = "SharedFramework"
            }
        }
    }
    macosX64("macos")
    linuxX64("linux")
    
    sourceSets {
        val commonMain by getting
        val iosMain by getting
        val macosMain by getting
        val linuxMain by getting
    }
}

This configuration sets up a project that targets iOS, macOS, and Linux, with shared logic in the commonMain source set.

Advantages of Kotlin/Native for Cross-Platform Development

Kotlin/Native is the backbone of multi-platform capabilities of Kotlin, allowing one to implement cross-platform applications with the ability to target platforms beyond the JVM like iOS, Windows, Linux, and WebAssembly. Using Kotlin/Native, developers can share logic across platforms while leveraging platform-specific features when needed. Here are the main benefits of Kotlin/Native for cross-platform development:

1. Seamless Code Sharing Across Platforms

Shared Common Business Logic and Code across Many Platforms. It considerably reduces duplicated code when it uses shared common business logic and code across platforms.

• Shared codebase: Use common functionality once throughout the development of multiple applications that differ by platform (e.g. Android, iOS, web), to thereby make the development much more efficient and ensure that the applications have the same underlying logic.
• Platform-Specific Implementations: Kotlin/Native allows for most code sharing but permits platform-specific implementations whenever needed-e.g., UI components-whose designers have flexibility and where one can optimize their code to better perform.

2. Native Performance

Kotlin/Native compiles directly into native binaries, rather than running on a virtual machine, which achieves high performance on the target platform.

• No Java Virtual Machine Overhead: Kotlin/Native runs natively, uses less memory, and executes faster, especially on platforms like iOS and embedded systems, because JVM-based languages cannot be applied.
• More Efficient Memory Management: Kotlin/Native offers a more efficient runtime with mechanisms for the manual or automatic management of memory, well-suited to native development environments .

3. Better Interoperability with Platform-Specific Code

Kotlin/Native shows very good interoperability with other platform-specific languages so that one can use APIs and libraries native for platforms.

• Objective-C and Swift on iOS: Seamless integration with Objective-C and Swift on iOS makes it possible to reuse any of the existing iOS libraries or frameworks when writing core logic in Kotlin.
• Calling C libraries is supported: which can be useful for applications built based on lower-level system functionalities or legacy C/C++ codebases.
• Multiplatform Tooling: Kotlin/Native plays very well with known tools specific to each platform, including Xcode for iOS development and Gradle for Android and backend systems, making it easier to develop between platforms.

4. More Productive Developers

The result of applying cross-platform development with the use of Kotlin/Native leads to faster cycles and less code that needs to be maintained.

• Unified Codebase: This way, the core logic for Android and iOS can be managed by a single development team, instead of different teams or redundant work, resulting in higher productivity.
• Familiar Syntax: Developers familiar with JVM development in Kotlin will switch to Kotlin/Native instantly because there won’t be a completely new language or paradigm to learn and the transition will be easier, as well as the learning curve.
• Faster Iterations: Shared Business Logic: Reuse shared business logic for faster iterations over features, fixes, and updates with reduced development time and effort overall.

5. Reduced Maintenance and Cost

Maintenance efforts are cut down and cost of developing the project is minimum in shared Kotlin/Native business logic.

• Consistency Across Platforms: Using the same logic across platforms would have fewer chances of inconsistencies between platforms, hence fewer bugs, and easier maintenance of the application.
• Lower Long-Term Costs: To small and mid-size teams, fewer resources are to be consumed during maintenance and development of separate code bases for every different platform, hence the project becomes more economical in the long run.
• Simplified Debugging: Errors in the code that are common to the two logics have to be fixed only once. This makes the debugging quite simplified and lowers the cost in maintaining the code.

6. Cross-Platform Tooling and Ecosystem

The tooling made available for Kotlin allows Kotlin/Native to take full advantage of cross-platform development easily
Gradle Integration: The integration of Kotlin/Native with the Gradle build system is seamless. This brings along powerful build tools and standard dependency management for cross-platform projects.

• Multiplatform Libraries: The Kotlin ecosystem has expanded increasingly to multiplatform libraries that truly integrate well with Kotlin/Native, such as Ktor, which is networking, kotlinx.serialization, which is serialization, and Kotlinx.coroutines, which is asynchronous programming. These lessen the requirement of re-inventing common functionality across platforms.
• IDE Support: Kotlin’s IntelliJ IDEA and Android Studio are both ideal for developing applications in Kotlin/Native, since they incorporate features like code completion, refactoring, and debugging in cross-platform projects.

7. Native APIs availability

Of course, for engineers, Kotlin/Native opens the possibility of direct access to platform-native APIs, which could lead to deeper integration with some platform-specific functionalities.

• Native iOS Access: Kotlin/Native, through interoperability between Objective-C and Swift, provides full access to iOS native APIs, allowing a simple use of iOS frameworks such as UIKit or Core Data while writing shared logic in Kotlin.
• Native Libraries Access: On Windows, Linux, and macOS platforms, Kotlin/Native can call system APIs or interact directly with C libraries, thus allowing the native development of applications that deeply integrate with the OS.

8. Suitability for Mobile and Embedded Development

Kotlin/Native is particularly suited for developing mobile (iOS, Android) and embedded systems where native performance and control at the lower levels are at premium.

• Mobile Development: Kotlin/Native fits very well in cross-platform mobile application development, where the business logic can be shared between Android and iOS while maintaining native look and feel for the UI of each platform.
• Embedded Systems: For platforms which cannot execute the JVM-as is the case with most IoT devices or microcontrollers, Kotlin/Native offers a way to write Kotlin code which then compiles to native executables.

9. Encourages Code Reuse

The Kotlin Multiplatform approach, powered by Kotlin/Native, encourages reusability of core components and code.

• Library and Framework Sharing: Common business logic, algorithms, or data models can be shared across different target platforms, reducing code duplication and encouraging the creation of reusable libraries.
• Consistency Across Applications: Sharing the same logic ensures that features, calculations, and data handling behave consistently across all target platforms, improving the user experience.

Disadvantages of Kotlin/Native for Cross-Platform Development

While Kotlin/Native offers numerous advantages for cross-platform development, it also comes with several disadvantages that developers should be aware of. These challenges can impact the effectiveness and efficiency of using Kotlin/Native in certain scenarios. Below are the primary disadvantages of Kotlin/Native for cross-platform development:

1. Limited Ecosystem Compared to JVM

Kotlin/Native is still relatively new compared to the JVM version of Kotlin, resulting in a smaller ecosystem of libraries and frameworks.

• Fewer Libraries: While Kotlin has a rich ecosystem for the JVM, many libraries are not yet available or fully supported in Kotlin/Native, limiting developers’ options when it comes to third-party tools and utilities.
• Limited Community Support: The Kotlin/Native community is not as large as the JVM community, which can lead to fewer resources, tutorials, and community-driven projects specifically targeting Kotlin/Native.

2. Learning Curve and Complexity

Transitioning to Kotlin/Native may involve a learning curve for developers accustomed to JVM Kotlin.

• New Paradigms: Developers may need to adapt to new paradigms and concepts, such as working with native memory management and dealing with platform-specific differences.
• More Complexity in Interoperability: Managing interoperability with Objective-C, Swift, and C can introduce complexity, especially for those unfamiliar with native development practices.

3. Increased Build Time

Kotlin/Native can result in longer build times compared to traditional Kotlin applications.

• Compilation to Native Code: The process of compiling Kotlin code to native binaries can be slower than compiling to JVM bytecode, leading to longer build and iteration times.
• Incremental Builds: While improvements have been made, incremental builds in Kotlin/Native may not be as efficient as in JVM-based projects, which can hinder development speed.

4. Platform-Specific Limitations

Kotlin/Native may not provide full access to all features available on each platform, which can limit the ability to utilize platform-specific capabilities.

• API Availability: Some APIs may not be available or fully supported in Kotlin/Native, restricting the use of certain platform features or requiring fallback implementations.
• Fragmentation: Differences in behavior between platforms can lead to fragmentation, requiring developers to write more conditional code to handle various platform-specific scenarios.

5. Runtime Limitations

Kotlin/Native has certain runtime limitations compared to the JVM, which can affect performance and functionality.

• No Garbage Collection: Kotlin/Native uses manual and automatic memory management instead of a garbage collector, which can lead to memory management issues if not handled properly.
• Potential Performance Overheads: While Kotlin/Native is designed for performance, there may still be overheads in certain scenarios compared to fully native languages like Swift or C++.

6. Debugging Challenges

Debugging Kotlin/Native applications can be more complex compared to traditional Kotlin/JVM applications.

• Limited Debugging Tools: The debugging experience may not be as mature as in JVM-based development, making it harder to diagnose issues.
• Native Debugging Complexity: Working with native code can introduce additional complexity in debugging, especially when integrating with platform-specific libraries and APIs.

7. Compatibility and Stability

Kotlin/Native is still evolving, which can lead to issues with compatibility and stability.

• Frequent Updates: The rapid evolution of Kotlin/Native may lead to breaking changes or instability in certain libraries and features, potentially causing issues during development.
• Backward Compatibility: Compatibility with previous versions of Kotlin/Native may not always be guaranteed, which can complicate maintenance and updates for long-term projects.

8. Limitation of UI Development

Even though perfect for business logic, Kotlin/Native may lack strong solutions to UI development across all platforms.

• Lack of Unified UI Framework: Developers would probably end up using individual platform UI frameworks that is SwiftUI for iOS and Jetpack Compose for Android. This would naturally lead to code duplications of UI components.
• Inconsistent User Experience: Ensuring a consistent user experience is probably going to be quite challenging for the developers as different platforms such as Android and iOS have different UI elements and design paradigms.