Swift and Kotlin are the two modern languages used to build native applications for Android and Apple devices. Here we will compare Swift vs Kotlin based on syntax, performance, ecosystem, error handling, security, scalability, supported platforms, hardware requirements, and learning curve.

Introduction

Swift

Swift is a powerful and intuitive programming language for all Apple platforms. It’s easy to start using Swift, with a concise yet expressive syntax and modern features you’ll love. Swift code is safe by design and produces software that runs lightning‑fast.

Swift has replaced Objective C which has been used to make iOS apps. It is a statically typed, null-safe language, that supports functional and object-oriented programming. Features like type inference, extensions, closures, data class, etc make Swift a modern language

We can craft modern user interfaces with Swift, using libraries like UIKit and SwiftUI.

Kotlin

Kotlin is a programming language that makes coding concise, cross-platform, and fun. It is Google's preferred language for Android app development. It's a modern alternative to Java for mobile application development. With newer versions of Android Studio, Kotlin is the default language for making Android apps rather than Java.

Kotlin code is compiled into Java and then uses JVM to run on the system. But Its easy syntax, less boilerplate code, and features like Null safety, extension functions for enhancing existing classes, closures, lambda expressions, data classes, etc. make it more powerful and developer-friendly.

It has libraries like Jetpack Compose which is used to make ui with code, no XML is required.

Similarities

These are some similarities and differences between Swift and Kotlin

• Null Safety: Both languages emphasize safety by providing mechanisms to handle nullability, reducing the risk of runtime crashes.
• Type Inference: Swift and Kotlin can automatically infer variable types, allowing for cleaner and more concise code.
• Extension Functions: Both support extending existing classes with new functionality without modifying their source code.
• First-Class Functions: Both languages treat functions as first-class citizens, allowing for higher-order functions and functional programming paradigms.
• Data Classes (Kotlin) / Structs (Swift): Both provide concise ways to define simple data-holding classes, with automatic generation of common methods.
  
• Interoperability: Swift can seamlessly integrate with Objective-C, while Kotlin is fully interoperable with Java, making it easier to adopt in existing codebases.
  
• Modern Syntax: Both languages feature clean and expressive syntax, enhancing readability and maintainability.

Difference

A few differences between Swift and Kotlin

• Platform: Swift is primarily for iOS and macOS development, while Kotlin is mainly used for Android but also supports server-side and cross-platform applications.
• Interoperability: Swift interoperates with Objective-C, whereas Kotlin is fully interoperable with Java, allowing easy integration with existing codebases.
• Language Paradigms: Swift emphasizes protocol-oriented programming, while Kotlin supports both object-oriented and functional programming paradigms.
• Memory Management: Swift uses Automatic Reference Counting (ARC) for memory management, while Kotlin relies on garbage collection via the JVM.
• UI Frameworks: Swift utilizes SwiftUI for declarative UI development, whereas Kotlin traditionally uses XML layouts in Android, though Jetpack Compose introduces a declarative approach.

Syntax

These are some basic syntax and styles for writing Swift vs Kotlin Code.

Variable Declaration

Swift: Uses let for constants and var for variables.

let constantValue = 10
var variableValue = 20

val constantValue = 10
var variableValue = 20

func greet(name: String) -> String {
    return "Hello, \(name)!"
}

fun greet(name: String): String {
    return "Hello, $name!"
}

let score = 85
if score > 90 {
    print("A")
} else if score > 80 {
    print("B")
} else {
    print("C")
}

val score = 85
if (score > 90) {
    println("A")
} else if (score > 80) {
    println("B")
} else {
    println("C")
}

Performance

Swift

• Swift is known for its high performance, often comparable to C++. It compiles native code, enabling efficient execution on iOS devices.
• Memory Management: Swift uses Automatic Reference Counting (ARC) to manage memory, which can lead to performance optimizations, but requires careful handling of retain cycles.
• Concurrency: With the introduction of structured concurrency in Swift, it offers efficient thread management, enhancing performance in multitasking applications.

Kotlin

• Kotlin, when compiled to native code via Kotlin/Native, offers good performance, though it may not match Swift’s execution speed on iOS.
• JVM Compatibility: When run on the Java Virtual Machine (JVM), Kotlin leverages the performance optimizations of the JVM, making it suitable for Android development.
• Coroutines: Kotlin's coroutines provide an efficient way to manage asynchronous tasks, improving performance and responsiveness in applications.

Both Swift and Kotlin offer strong performance for their respective platforms. Swift is optimized for iOS with a focus on native execution, while Kotlin provides flexibility with JVM and native compilations. The choice between them often depends on the platform rather than raw performance.

Ecosystem

Swift Ecosystem

• Development Environment: Primarily developed using Xcode, which provides a robust IDE with integrated tools for debugging, testing, and UI design.
• Libraries and Frameworks: Swift benefits from a rich ecosystem of libraries, especially through frameworks like UIKit and SwiftUI for UI development, and Foundation for core functionalities.
• Community and Support: Strong community support with resources like Swift.org and numerous open-source projects. Apple's documentation and developer forums are also valuable resources.

Kotlin Ecosystem:

• Development Environment: Commonly developed in Android Studio, which provides extensive support for Android app development and integrates well with Gradle for build management.
• Libraries and Frameworks: Kotlin has a vast ecosystem, especially for Android, with libraries like Ktor for networking, Koin for dependency injection, and Jetpack for various Android components.
• Cross-Platform Development: Kotlin Multiplatform allows for shared codebases across platforms (iOS, Android, web), promoting code reuse and reducing development effort.

Swift's ecosystem is heavily focused on iOS/macOS development, supported by Apple's tools and frameworks. In contrast, Kotlin's ecosystem is versatile, excelling in Android development and offering cross-platform capabilities, making it a strong choice for multi-platform projects.

Error Handling

Swift 

• Mechanism: Swift uses a combination of try, catch, and throw for error handling, allowing developers to handle errors explicitly and clearly.
• Optionals: Swift's optional types help prevent runtime crashes by forcing developers to handle the absence of a value safely.

Example

enum CustomError: Error {
    case somethingWentWrong
}

func riskyFunction() throws {
    throw CustomError.somethingWentWrong
}

do {
    try riskyFunction()
} catch {
    print("Error: \(error)")
}

fun riskyFunction() {
    throw Exception("Something went wrong")
}

try {
    riskyFunction()
} catch (e: Exception) {
    println("Error: ${e.message}")
}

Security

Hardware & Code Editor(IDE) Required

Swift and Kotlin require a decent amount of hardware resources to run the IDE, write code, run emulators, and build apps. Here we will compare the minimum hardware requirements needed for Swift vs Kotlin.

Swift

Swift is used to write applications for Apple platforms like iOS, macOS, tvOS, and watchOS. XCode is the editor for writing Swift codes. It contains all the dependencies, emulators, and development environments needed to run Swift. Once we have installed XCode, all things come included.

XCode is not available on Windows and Linux, you'd need a Mac for this. A Mac mini or Mac Book Air with 8GB RAM will be enough to build iOS apps and Run them on a Simulator.

* We can also install Swift on a Windows and Linux PC and write basic codes, but without XCode, we can't build apps. This is the entry barrier to becoming an iOS developer. 

You can download Swift for Windows and Linux from here and write Swift code. 

Kotlin

Kotlin is a general proposed program like Java and can run on any system with Kotlin installed. It's majorly used to build Android Apps and Cross-platform apps with Kotlin Multiplatform. With Kotlin Multiplatform we can build apps for the web, android, and iOS.

Generally, Android Studio is used to write Kotlin code for Android Studio. For Kotlin multiplatform we can use Android Studio and XCode for building apps. But also we can use VSCode to write Kotlin codes.

So we can install and run Kotlin on Windows, Mac, and Linux. Any decent machine with 8GB RAM and an i5/r5 processor can run the Kotlin apps. But to have a smooth development recommended to go with 16GB RAM. 

Learning Curve

Swift and Kotlin, both are good languages to start with. Most of the features are similar with a slight difference in syntax and working. The learning curve will be somewhat similar for both. You can start your journey in one of these with an effort of 3-6 months.

The major difference is to know the design principles of iOS and Android. Swift primarily targets the Apple Platform and Kotlin Targets Android Platforms.