Comparison of Kotlin vs. Swift: How To Choose Better Language?

21 May 2024
Paweł Ługowski
Paweł Ługowski
Android Developer
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Contents

  • Intro

Swift and Kotlin are arguably one of the most popular modern coding languages, especially in the mobile realm. The differences between them seem quite straightforward, as they are associated with specific app development services. Kotlin is the preferred choice for Android programming, while Swift is associated with iOS development

However, these two languages do share several similarities and overlapping use cases. So how do you choose the better language between them? In this post, we’ll compare Kotlin and Swift, exploring their differences, similarities, pros and cons.

  • Kotlin is the preferred choice for Android programming, while Swift is associated with iOS development.
  • Both Swift and Kotlin excel in terms of their ease of use, performance and safety, which is why they’re preferred over older languages. 
  • Although it is mainly used for Android app development, Kotlin makes it easy to build apps for multiple operating systems using the same code base. 
  • Your choice between Kotlin and Swift depends on the operating system you’re building for. 

What is Swift Programming Language?

Swift is a general-purpose software programming language developed by the Apple Company originally for iOS app development. It was created in 2014 and released a year later as a replacement programming language for C-based languages (Objective C, C++, and C) previously used by the Apple platform as its primary language. Swift was initially released as a proprietary programming language. However, Apple later released it as an open-sourced software in December 2015. 

Today, Swift is used for building apps for various Apple-owned operating systems such as iOS, macOS, watchOS, and tvOS. However, Swift is an open-source programming language and this has led to its adoption as a development language across several other platforms beyond Apple’s ecosystem. The open-sourced nature of this programming language has also allowed community contributions and adoption for various other use cases.

Apple developed Swift with performance and safety in mind. In essence, Swift was created to make the process of writing, maintaining, and correcting software code considerably easier for developers.

By creating Swift, Apple sought to eliminate common programming errors such as null pointer dereferencing that plagued older languages and made them unsafe. It also featured a simple syntax that simplified app development and ensured it was faster and more reliable than alternatives. Swift is up to 2.6 times faster than the Objective-C programming language and 8.4 times faster than Python.

The simplicity and ease of use of this programming language have favored its popularity and adoption by developers. Currently, the language is ranked 9th on the PYPL chart of most used coding languages, with a market share of 2.75%.

Companies Using Swift

  • Uber 
  • IBM
  • Slack 
  • Facebook 
  • Airbnb 
  • Coursera 
  • LinkedIn 

What is Kotlin Programming Language?

Kotlin is a statically typed, cross-platform object-oriented programming language developed by JetBrains in collaboration with Google. It is a modern language released in 2011 as an alternative to the Java Programming language for Android app development. In fact, just like Java, which was named after the Indonesian Island of Java, Kotlin was named after Kotlin Island, a Russian island in the Gulf of Finland. 

Kotlin was introduced by JetBrains as a new language for the Java Virtual Machine to make up for some of the deficiencies of the Java programming language while also ensuring quick and efficient development. While Scala, another JVM programming language, had many of the features JetBrains wanted to fix in Java, it didn’t compile quickly enough. Consequently, the company built Kotlin to achieve this goal. 

However, while it was developed as a better alternative to Java, one of the goals of creating Kotlin was interoperability. Consequently, this programming language was built to be fully compatible with Java Code, Java Class Libraries, and Android Studio. Kotlin’s interoperability has allowed its adoption for a wide range of use cases beyond just building Android apps. 

Kotlin was originally released as a proprietary project by JetBrains. However, it has been made open source by the company since 2012. In 2019, eight years after it was released, Google announced it was officially adopting Kotlin as its preferred programming language for Android app development. This language currently ranks 13th on the PYPL chart of most used programming languages in the world, with a market share of 1.75%. 

Companies Using Kotlin

  • Netflix 
  • Pinterest 
  • Evernote 
  • Duolingo 
  • Kickstarter

Pros and Cons of Swift

Advantages

  • Supports Rapid Development: To rebuild the Lyft app from scratch with Swift, the company only wrote one-third of the original 75,000 lines of code in the original version. This demonstrates how the simplified language syntax of Swift makes it a faster way to write code for apps compared to older languages. 
  • Scalability: In addition to ensuring quick development, apps built with Swift are also easy to scale. The language makes it easier to extend their functionalities by adding new features. 
  • Improved Performance: Swift is built to outperform older programming languages like Objective-C code. The fact that it is optimized for Apple’s hardware further makes it the best language for iOS development. 
  • Safety: The Swift code syntax encourages users to write consistent and error-free code. This also makes it easier to catch errors while writing instead of spending hours debugging code. Swift features various error-handling functions that help prevent code crashes and make it a safer way to code.   
  • Interoperability with Objective-C: While it is often considered an alternative to Objective-C, Swift is actually quite compatible with the older programming language. Consequently, you can use Swift in older Objective-C projects or incorporate Objective-C elements in your Swift project. 

Disadvantages

  • Talent pool is limited: Despite growing demand for Swift developers, the language is still in its infancy. Consequently, the talent pool of developers learning Swift is a lot less compared to older languages, which makes it difficult to find an experienced programmer.  
  • Does not support older iOS versions: Swift cannot be used to build apps for iOS operating systems older than IOS7. 
  • Swift is unstable: as new versions of Swift are released, there’s a lack of backward compatibility between older and newer versions. This can also make it difficult to find appropriate third-party tools and IDE that are compatible with what you’re building. 

Pros and Cons of Kotlin

Advantages

  • Kotlin is concise and readable: Kotlin has a simple syntax characterized by data classes, smart casts, and a type interface. This allows developers to build the same functionality while writing less code compared to older programming languages. 
  • Easier to catch bugs: Kotlin’s readability makes it easier to catch bugs. This programming language also comes with its own Compiler, which helps to detect errors and bugs while compiling the code instead of waiting till runtime. 
  • Interoperable: Kotlin is designed to be 100% interoperable with Java and other related tools and frameworks. This allows you to easily switch from one of these to the other or combine them seamlessly, especially for products that cannot be written solely in Kotlin.
  • Kotlin resolves several Java issues: Kotlin was created to resolve various inadequacies with Java. For instance, unlike Java which was mainly geared towards object-oriented programming, Kotlin allows both functional and object-oriented constructs. Kotlin also handles NullPointerException issues better, making it more stable and reliable. 
  • Kotlin supports cross-platform development: Kotlin makes it easy to build apps for other mobile platforms. The Kotlin Multiplatform Mobile SDK for instance, makes it easy to share the business logic of your app for different operating systems, including mobile and desktop applications. It is also easy to compile Kotlin code to JavaScript.  This is why Kotlin is the preferred language for building apps for multiple platforms

Disadvantages

  • Problems with the compilation speed: Although Kotlin apps are lightweight and the compiler is great, especially for incremental builds, the compilation build might be a little slow for clean builds. 
  • Limited availability of developers: One of the biggest problems with most languages that are relatively new on the horizon, like Kotlin, is that not many developers are learning them compared to legacy languages like Java. Consequently, finding and hiring new talents for Kotlin projects can be a little difficult. 
  • Young ecosystem: Kotlin’s ecosystem is younger compared to Java’s robust and long-established ecosystem. While Kotlin’s popularity has grown significantly, leading to an expanding ecosystem, it still doesn’t match the extensive range of resources available for Java. The Kotlin developer community is growing rapidly, but it is smaller than Java’s, which means there may be fewer resources for learning or troubleshooting issues. 

Kotlin vs Swift: Main Differences

Primary Development Platform 

Kotlin is primarily used for Android development, while Swift is used for iOS. However, they both support multi-platform development, with Kotlin being the more robust option for this as it is more of a general-purpose language. Both languages are known for their ease of use and general efficiency in coding. 

Function Implementation

Kotlin and Swift approach function implementation differently, which is one of their key distinctions. In Swift, an underscore (_) can be used as a prefix for parameter names to indicate that the argument label should be omitted when calling the function. In contrast, Kotlin does not use underscores in this manner.

Data Class 

The data class is one of the most basic concepts across various programming languages. Class is used to hold data and it also drives some standard functionality. Kotlin development uses classes but the concept isn’t available in Swift. The latter utilizes struct instead. 

Memory Management

Kotlin uses the Garbage Collection Approach (GCA) for memory management while Swift uses Automatic References Counting (ARC). Generally, the Arc approach is considered more precise and efficient.

Concurrency

Kotlin uses coroutines for asynchronous programming, which are lightweight threads that allow writing asynchronous code in a sequential manner. Swift uses Grand Central Dispatch (GCD) and Operation Queues instead, and more recently, introduced Swift Concurrency with async/await and actors to manage concurrency more safely and efficiently.

Kotlin vs Swift: Main Similarities

Modern Syntax 

Both Swift and Kotlin are characterized by clean and concise syntax which makes them easier to learn, write, and read compared to older alternatives. This in turn improves developer productivity. 

Type Safety 

Both languages are statically typed. Consequently, the variable types are declared during compilation and this helps to catch errors early during the development process. 

Memory Management 

While there are notable differences between them, the memory management systems used by Swift and Kotlin (ARC and Garbage Collection respectively) are automatic. This helps to free up development time and ensure stable memory management. 

Functional Programming 

Unlike older alternatives that support object-oriented programming alone, Kotlin and Swift support functional programming concepts such as immutability, higher-order functions, closures, and more. This makes them more efficient, especially for data manipulation. 

Error Handling

Kotlin and Swift are known for their robust error-handling features such as try-catch blocks and optional/nullable types. These features allow developers to efficiently handle potential errors during application execution.

Extensions

With Swift code, developers can add additional functionality to their code by using extensions. Kotlin allows users to add or alter parts of the default feature code as well.

Enumerations 

Also known as Enums, this is a specific set of values used to protect data while coding and can help speed up programming. You can easily create enum data types both in Swift and Kotlin.

What To Learn For Mobile App Development: Swift or Kotlin?

Choosing between each of these programming languages shouldn’t be difficult. Both are efficient modern alternatives to older languages for mobile app development. They’re known to be easy to learn and they make writing code considerably easier. 

So should you learn Kotlin or Swift? It all depends on the type of mobile applications you want to build. Kotlin is mainly for Android apps while Swift lets you build apps for iPhones and Mac OS. Kotlin does give you an edge if you’re looking for a more general-purpose programming language that can be used to build for both platforms. The Kotlin Native platform allows you to create mobile apps for both iOS and Android operating systems using a single codebase.

Conclusion

Kotlin and Swift are two innovative coding languages, popular as more efficient replacements for older programming languages. They have been adopted by popular names in the industry and are used by some of the biggest organizations in the world for app development. 

There’s no doubt that these two coding languages will shape the iOS and Android development world in the coming years. They’re both worth learning or adopting for your app development needs. However, your choice between these two options depends on what you’re building, the development platform, and the specific features you hope to prioritize for your project.

FAQ

  • Is Swift or Kotlin better for mobile apps?

    It’s hard to pick a “better” programming language between these two options, mainly because they both have their unique use cases. Swift is ideal for iOS, iPadOS, macOS, watchOS, and tvOS development while Kotlin is the official language for the Android operating system. Your choice between these two depends on the platform you’re building for.

  • Which came first, Kotlin or Swift?

    Kotlin came first. Swift was first released to the public in June 2014 while Kotlin was unveiled a few years earlier in 2011.

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