Swift.org
On December 3, 2015, Apple officially released the Swift language, supporting libraries, the debugger, and the package manager to the open source community under the Apache 2.0 license. At that time, the swift.org site was created as the community's gateway to the project. This site has a wealth of information and should be your primary site to find out what is happening in the Swift community and the language itself. The blog posts will keep you up to date with new releases of Swift, new Swift open source libraries, changes to the standard library, and other Swift news.
You can also download pre-built binaries for several flavors of Linux. At the time this book is being written, we can download pre-built binaries for Ubuntu 16.04, Ubuntu 18.04, Ubuntu 20.04, CentOS 8, and Amazon Linux 2. The getting started page provides a list of dependencies for the previously mentioned flavors of Linux and instructions on how to install the binaries.
The website...