In our article about THE BEST PROGRAMMING LANGUAGES TO LEARN IN 2021, we presented Swift, a programming language for macOS, iOS, watchOS, tvOS and beyond.

Swift is the result of the latest research on programming languages, combined with decades of experience building Apple platforms. Named parameters are expressed in a clean syntax that makes APIs in Swift even easier to read and maintain. Even better, you don’t even need to type semi-colons. Inferred types make code cleaner and less prone to mistakes, while modules eliminate headers and provide namespaces. To best support international languages and emoji, Strings are Unicode-correct and use a UTF-8 based encoding to optimize performance for a wide-variety of use cases. Memory is managed automatically using tight, deterministic reference counting, keeping memory usage to a minimum without the overhead of garbage collection.

Swift has many other features to make your code more expressive:

• Generics that are powerful and simple to use
• Protocol extensions that make writing generic code even easier
• First class functions and a lightweight closure syntax
• Tuples and multiple return values
• Structs that support methods, extensions, and protocols
• Enums can have payloads and support pattern matching
• Functional programming patterns, e.g., map and filter
• Native error handling using try /catch/ throw

Designed for Safety

Swift eliminates entire classes of unsafe code. Variables are always initialized before use, arrays and integers are checked for overflow, memory is automatically managed, and enforcement of exclusive access to memory guards against many programming mistakes. Syntax is tuned to make it easy to define your intent — for example, simple three-character keywords define a variable ( var ) or constant ( let ). And Swift heavily leverages value types, especially for commonly used types like Arrays and Dictionaries. This means that when you make a copy of something with that type, you know it won’t be modified elsewhere.

Fast and Powerful

From its earliest conception, Swift was built to be fast. Using the incredibly high-performance LLVM compiler technology, Swift code is transformed into optimized native code that gets the most out of modern hardware. The syntax and standard library have also been tuned to make the most obvious way to write your code also perform the best whether it runs in the watch on your wrist or across a cluster of servers.

Swift is a successor to both the C and Objective-C languages. It includes low-level primitives such as types, flow control, and operators. It also provides object-oriented features such as classes, protocols, and generics, giving Cocoa and Cocoa Touch developers the performance and power they demand.

Source and Binary Compatibility

With Swift 5, you don’t have to modify any of your Swift 4 code to use the new version of the compiler. Instead you can start using the new compiler and migrate at your own pace, taking advantage of new Swift 5 features, one module at a time. And Swift 5 now introduces binary compatibility for apps. That means you no longer need to include Swift libraries in apps that target current and future OS releases, because the Swift libraries will be included in every OS release going forward. Your apps will leverage the latest version of the library in the OS, and your code will continue to run without recompiling. This not only makes developing your app simpler, it also reduces the size of your app and its launch time.

Open Source

Swift is developed in the open at Swift.org, with source code, a bug tracker, forums, and regular development builds available for everyone. This broad community of developers, both inside Apple as well as hundreds of outside contributors, work together to make Swift even more amazing. There is an even broader range of blogs, podcasts, conferences and meetups where developers in the community share their experiences of how to realize Swift’s great potential.

Cross Platform
Swift already supports all Apple platforms and Linux, with community members actively working to port to even more platforms. With SourceKit-LSP, the community is also working to integrate Swift support into a wide-variety of developer tools. 

Swift for Server
While Swift powers many new apps on Apple platforms, it’s also being used for a new class of modern server applications. Swift is perfect for use in server apps that need runtime safety, compiled performance and a small memory footprint. To steer the direction of Swift for developing and deploying server applications, the community formed the Swift Server work group. The first product of this effort was SwiftNIO, a cross-platform asynchronous event-driven network application framework for high performance protocol servers and clients. It serves as the foundation for building additional server-oriented tools and technologies, including logging, metrics and database drivers which are all in active development.

Objective-C Interoperability

You can create an entirely new application with Swift today, or begin using Swift code to implement new features and functionality in your app. Swift code co-exists along side your existing Objective-C files in the same project, with full access to your Objective-C API, making it easy to adopt.