To write server apps in Swift, we require an understanding of where Swift comes from and how it fits into the world of server languages. Swift was invented by Apple engineers as an alternative to C-derivatives, for example, C++, and, Objective-C, Objective-C++. After initially keeping Swift proprietary Apple then released Swift as open source for macOS and Linux. You might have wondered why Apple would bother to make Swift available on Linux, as Apple doesn't usually release any Linux products (not even iTunes).

Swift was designed to be a native language from the very beginning. It means an application gets compiled into binary code that runs directly on the processor, making it the fastest way for an application to run.

When Apple released Swift for Linux, there was little application. The UI was still functioning only on Apple devices, but a good bit of the essential frameworks, Foundation, in particular, was functional on Linux. These frameworks opened the door for some early web frameworks that took Swift and connected it to C libraries that would allow Swift code to run as a web server.

The Perfect framework was the first framework that did this. In September 2016, Tanner Nelson wrote the first version of the Vapor framework, which was loosely based on the Laravel framework (PHP). In May 2017, Vapor 2 was released, which was the first Swift framework that didn't rely on a C library to provide web server functionality. In the meanwhile, IBM started to work on Kitura, yet another framework allowing Swift to be used for web applications.

In early 2018, Apple released SwiftNIO, which is a network library for Swift. You can think of it as "Netty for Swift" if you are familiar with Netty (Java). To put it simply: SwiftNIO provides a very foundational framework to operate in a network and in files, such as opening connections, sending data, receiving data, sending streams, reading streams, and similar operations.

By releasing SwiftNIO, Apple now gave developers an essential set of features to work on server applications. SwiftNIO, like Swift, was also released for Linux.

Let's take a brief look at the history of Swift in the context of other programming languages.

In this section, we want to take a look at the development of Swift, from Fortran, a very old programming language, up until Swift.

The following diagram and the timeline next to it highlights well how Swift combines the best of numerous worlds:

It stands out that Swift was influenced by Rust, Ruby, Python, Haskel, and C#, making it a very modern language that copied some of the most loved features of the other languages.

Now, we have learned about the history of Swift and where its place is in the world of programming languages. Let's look at Swift's performance compared to other popular web technologies next.