Kotlin Vs. Swift: 13 Differences That Every Developer Should Know


27 Dec, 2019


5 min read

Kotlin vs Swift

Coding skills are highly coveted in the tech industry. With digitalization on the rise, many companies seek development services to secure their position in the mobile app market and the World Wide Web.

Java, Swift, Kotlin, and Objective-C are the tools of the trade for a developer. They are the languages in which a developer converses with a machine to design their digital products. Brian Kernighan defines programming language as being

specific to instructing a computer to do a particular structure of a sequence. It’s the way you tell the machine what you want it to do.”

Kotlin and Swift are two of the promising programming languages offering swift development, ease of coding, and evolving features. They share plenty of similarities, one of which is the lack of platform-specificity. Meaning, developers can use Kotlin for iOS and Swift for Android apps.

Let’s dive and explore the depth of these programming languages, the similarities they share, and the differences:

Define the Language

Kotlin is based on an LLVM architecture featuring Java Virtual Machine. It is the best alternative to Java for Android OS with a low learning curve and the ability to counter the limitations of Java, including lengthy source code and runtime exceptions.

Kotlin shares a similar structure to Java, with new features, cleaner syntax, security, and clarity, which makes it interoperable. It offers faster development and access to Java libraries and frameworks. Additionally, it is less susceptible to coding errors because of the lack of null point exceptions.

Swift is also an open-source programming language explicitly designed to replace Objective-C. It is intuitive and curated with LLVM compiler infrastructure. Developers can use it for all Apple operating systems, including iOS, MacOS, and Linux. But, its similarity to Kotlin also allows developers to use Swift for Android.

Swift is interoperable with Apple’s frameworks, including Cocoa and Cocoa Touch. Additionally, Cocoa also happens to be a critical element in Swift’s infrastructure. Developers working with Swift can expect enhanced performing speed and security in the apps.

The Similarities

Kotlin and Swift are two programming languages that are fundamentally different from each other. Experts, however, feel that they share more similarities than differences as the two new emerging languages for app development.

First, the syntax for both languages is straightforward, more natural, and understandable. Secondly, Kotlin and Swift are functional languages prioritizing app function. Lastly, they both can deal with nullable and non-nullable types by referring to the differences.

With their syntaxes being almost similar, developers can switch from one language code to the other without hassle. SwiftKotlin is an open-source Mac platform that makes the conversion possible, despite how the two languages run in different environments, access different frameworks and system libraries.

Swift developers are sure to enjoy working with Kotlin and vice versa. For cross-platform development, you can work with Xamarin, React Native, Cordova, or low-level libraries. Both languages offer a simple learning curve, are concise and readable.

Kotlin Vs. Swift: 13 Differences that Matter [Infographic]

Both Kotlin vs. Swift are infinitely more intuitive and powerful programming languages than their predecessors, Java and Objective-C. They offer swift development of Android app development and iOS app development.

Here’s a Kotlin vs. Swift comparison for developers to understand the differences between the languages:


Kotlin and Swift are primarily for Android and iOS app development, respectively. They are gaining recognition and preference over other programming languages because of their easy-to-follow syntax, simple way of writing, and modern techniques.

Traditionally the two are platform-specific, Kotlin for Android and Swift for iOS. However, Kotlin Native allows developers to use it for hybrid development, targeting platforms that execute bytecode without VM.

Similarly, you can use Swift for Android. The Swift compiler creates a Swift code capable of running on Android OS, but it requires an integration of a framework to build a compatible UI for the app.

    Data Class

Kotlin features a data class where Swift does not. When writing the code, developers create classes with the intent to hold the data. These classes also automatically drive standard functionalities and utility functions. Data class in Kotlin, allows developers to implement things like impartiality and replication.

Swift has no counterpart for data class.

    Function Implementation

Kotlin and Swift share very slight differences in their function implementation. In Swift, the variable has an underscore (_) as a prefix, while Kotlin does not. Additionally, Kotlin has $ as a prefix with the variable name to return to the argument, and Swift features the variable in braces and forward slash ().

   Default Class

Kotlin classes do not allow any alterations or extensions. As a default feature, Kotlin does not allow developers to add extensions to the code.

     Error Handling

Kotlin and Swift differ in the keywords used to indicate an error, but their function is the same. Where Kotlin uses null for error handling in String variables, Swift uses nil.


Enums defines the enumerations in the coding under the Enum list, which contains a set of name limitations. In Swift, Enums perform computation properties, features of the Struct, and other values.

Kotlin does not have an Enum list, which results in a lack of Enums pattern during coding. Alternatively, these patterns can be gained by a sealed class, but it is a complicated technique.


Kotlin and Swift also differ in the Structs the developers can use.

Structs are generally passed by value or by reference. It means that every time developers call a method with it, return a struct, or assign a struct, the values are transferred to the new variable. Any modifications to the structure will only influence the modified variables, not the others.

Additionally, structs do not permit inheritance, which makes them ideal for data classes.

Kotlin has no specific Struct types as its function is similar to Java, where the fundamental types, int, float, and Boolean, are passed by value, and others by preference. Contrarily, Swift offers developers the flexibility to choose their preferred Struct or class based on their requirements.

    Memory Management

Swift offers more a concise and reliable memory management technique than Kotlin. Where Kotlin utilizes the Garbage Collection approach, Swift uses the ARC or Automatic References Counting.

Of the two methods, ARC is considered precision-driven and reliable.


Annotations allow developers to add metadata to the app code. Kotlin supports numerous annotations for app development while Swift does not, including @Target, @Repeatable, @Retention, @MustBeDocumented.


Tuples can be defined as a set of structured data with multiple parts. For example, in a relational database, the data is stored on Excel sheets with tuples defined as the rows. Its purpose is to help developers understand the interaction between different components where additional classes do not exist.

Kotlin does not feature any tuples types. Swift, however, uses it to outline the interfaces among components.

  Guard Statement

Guard statements are an alternative to the ‘if’ sentence for checking conditions of functions. Swift has guard statements, but Kotlin developers need to stick with the ‘if check’ then reverse the condition.

  Type Alias

Kotlin does not have type alias while Swift does.

  Delegated Class and Properties

Delegated properties award Kotlin another point over Swift. It allows developers to use method citations to other classes. Additionally, you can define traditional properties, including Lazy, Observation, and Storing properties.

Swift does not have delegated properties, so developers need to be satisfied with the default.

Kotlin or Swift for iOS and Android Development

The tech industry is continuously evolving. At the pace we are moving, innovations have become an everyday thing. Kotlin seems to dominate the Android app development market, while Swift is preferred for iOS app development.

Consult with our app experts that excel in both Kotlin and Swift programming languages. You can expect an app for iOS and Android apps with high-speed performance, excellent UI, and top-notch user experience.



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