Kotlin vs Swift: A Comparison and How to Choose

In this modern era of computing and constant connection, consumers, clients, and customers depend on mobile apps to make it easier to interact with your company, purchase your products, get information about a service, and even help promote your business. Across the globe, the most popular mobile platforms are Android and iOS. That means comparing Kotlin and Swift, the two most popular programming languages for Android and iOS (respectively).

Although the popularity of these two operating systems differs from region to region, there’s no escaping that your company should consider one or the other (or even both), to remain competitive in a very complex and growing market. Ultimately, this means you have to consider your market before selecting which language would best serve your company.

Before you decide, however, you might want to know a bit more about these two languages. Let’s dig into both.

What Is Kotlin?

At one point, Java ruled Android development. Although that has hardly changed, there is another language that has quickly come into favor by both Google and Android developers worldwide. That language is Kotlin. And although Java is still heavily used in the development of the Android operating system itself, on May 7, 2019, Google announced that Kotlin would become the de facto standard for Android app development.

Kotlin came into existence in July 2011. Dmitry Jemerov (lead JetBrains developer) realized that most languages (with the exception of Scala) didn’t include the features he needed. And even though Scala did include his desired features, it was far too slow at compiling code. Jemerov and JetBrains set out to create a language that had the features of Scala and the compile time of Java.

In February 2012, JetBrains open-sourced the new language under the Apache 2 license, naming it Kotlin, a name that was inspired by Kotlin Island, in a similar fashion to how Java was named after the Indonesian island.

At the moment, Kotlin’s TIOBE index is 35, while Java’s is 3, so clearly, Java is still far more popular than Kotlin. However, that doesn’t mean you’ll have any problem finding a Kotlin development company anywhere in the world. And as Android development continues to flourish, so too will Kotlin.

Advantages / Pros of Kotlin

Kotlin has a number of very important advantages over other languages that are used to develop Android applications. These advantages include the following:

• Less is more – With Kotlin, you’ll write less code. JetBrains did a great job of creating a very concise language. And because you’ll be writing less code, you’ll introduce fewer bugs.
• Written by those in the industry – Instead of being created within the realm of academia, Kotlin was created by those already in the industry, so they created a language that solved many challenges developers face.
• Easy to learn and adopt – Kotlin was created to be easy to use and adopt. And because Kotlin easily integrates (and is fully compatible) with Java, you can make it work with existing code.
• Zero runtime overhead – The Kotlin standard library was created to be lean and fast and mostly serves as an extension of the Java standard library.
• Multi-platform development – Not only can you use Kotlin for Android development but it also seamlessly integrates with JavaScript, so you can easily migrate your front-end apps to Kotlin with little effort.
• No null reference – British computer scientist, Sir Tony Hoare, once referred to the null reference as “the billion dollar mistake.” Kotlin’s type system practically eliminates null references.

Disadvantages / Cons of Kotlin

Although Kotlin does have plenty of advantages, it does include a few important disadvantages to make note of, such as:

• Fewer tools – Unlike Java, Kotlin doesn’t have nearly the number of third-party tools available.
• Slower compilations – Although the goal was to create a language that could compile as quickly as Java, Kotlin doesn’t quite achieve that mark.
• Smaller community – You will find Kotlin developers all over the world, but they aren’t quite as numerous as other languages higher on the TIOBE index.

What Companies Use Kotlin?

There are plenty of companies using Kotlin today, including the following:

• Udemy
• Slack
• Robinhood
• CRED
• Delivery Hero
• Tech Stack
• Tinder
• HENNGE K.K.
• Pinterest
• Postmates
• Uber
• Evernote
• Coursera

What Android App Development Tools Integrate with Kotlin?

Although you won’t find as many tools for Kotlin as you would for Java, there are still some important ones to keep in mind such as:

• Android Studio
• IntelliJ Idea
• Eclipse IDE
• Android KTX
• Jetpack Compose

What Is the Swift Programming Language?

As Kotlin is the official language for Android app development, Swift is the official language for iOS app development. Swift is a high-level, general-purpose programming language that was initially created in July 2010 by Chris Lattner. Eventually, a number of Apple programmers were added to the development of Swift.

Swift incorporated features from languages like Objective-C, Rust, Haskell, Ruby, Python, C#, and CLU. It wasn’t until June 2, 2014, at the Apple Worldwide Developers Conference, that Swift Apple released the first app built with Swift (which was the WWDC official app). Soon after that, a beta version of Swift was released by Apple.

Currently, Swift has a TIOBE index of 20, which makes it more popular than Kotlin but far less popular than Java. But because so many major markets are dominated by iOS devices, it’s very easy to locate and hire a Swift development service to help your company build and release apps to the Apple ecosystem.

Advantages / Pros of Swift

There are plenty of advantages to adopting Swift, such as:

• iOS app development – If you want to develop iOS apps, you have two choices, Objective-C and Swift.
• Easy to learn – Unlike Objective-C, Swift is considerably easier to learn.
• Fast development – Apple claims developing with Swift is 2.6 times faster than developing with Objective-C.
• Simple syntax and readability – Swift was created with the idea of creating a language with simple syntax and readability, which means maintaining code is considerably easier.

Disadvantages / Cons of Swift

Swift isn’t all advantages. Take these cons to heart when making your choice:

• A young language – Swift isn’t nearly as mature as many other languages. And although it has the full support of Apple, you might find the community and supporting tools to not be what you’re accustomed to.
• Backward compatibility – Swift does suffer from some backward compatibility woes. With each new version of the language, previous versions are not compatible.
• Limited – Swift is pretty much limited to developing for MacOS, iOS, iPadOS, Apple TV, and Apple Watch.

What Companies Use Swift?

Given how popular Apple products are, you can be sure there are plenty of companies currently using Swift, including:

• Uber
• Lyft
• Facebook
• Airbnb
• LinkedIn
• Asana
• Doordash
• Google

What Mobile App Development Tools Integrate With Swift?

There are plenty of tools available to Swift developers to help simplify development efforts, such as:

• SwiftLint
• Sourcery
• BartyCrouch
• SwiftGen
• Carthage
• SwiftFormat
• Fastlane
• SourceKitten

Key Differences Between Kotlin & Swift

There are some key differences between Kotlin and Swift that you should consider when choosing software development services, such as the following:

• Android vs. iOS – Kotlin is used for developing Android apps and Swift is used for developing iOS apps.
• Data classes – While Kotlin includes data classes (a way for developers to hold data), Swift does not.
• Underscore – Where Swift does make use of the underscore in variables as a prefix, Kotlin does not.
• Extensions – Swift allows extensions to add additional functionality but Kotlin does not.
• Error handling –  In Kotlin, errors are indicated with null, whereas Swift uses nil.

What Does the Future Look Like

There is no doubt that both Kotlin and Swift will continue to dominate mobile app development. Even though both Android and iOS apps can be developed with different languages (Java for Android and Objective-C for iOS), Kotlin and Swift are easier to use and therefore will only continue to grow in popularity.

Kotlin Versus Swift: Who Wins?

It depends on the market. For example, in the US and Japan, iOS is the dominant mobile platform, so if you’re a startup looking to settle on one app ecosystem or another, iOS and Swift are the best choice. However, if you’re looking toward India, where Android is massively more popular than iOS, the choice is simple.

If, however, you’re looking to develop an app for global use, you’ll probably want to adopt both languages.

When to Use Kotlin

The choice is simple. If you want to develop an Android application, choose Kotlin.

When to Use Swift

Again, the choice is quite simple. If your company is more focused on developing and releasing apps for the Apple ecosystem (iOS, MacOS, iPadOS, Apple TV, and Apple Watch), your only choice between these two would be Swift.