Swift is a programming language for iOS, macOS, iPadOS, watchOS, tvOS, and Linux applications. Apple introduced it in 2014, and since the release, it gradually becomes the most popular technology for iOS mobile apps. Swift became an open-source programming language at the end of 2015. Right now, we have almost 800 contributors that are actively improving the language. The latest version of Swift brings a wide number of changes and new features for iOS app developers. In the 1st quarter of 2020, users were able to choose between almost 1.85 million available apps for iOS.