Playgrounds can contain a mix of code and documentation. This allows a set of code samples and explanations to be mixed in with the playground itself. Although there is no way of using Xcode to add sections in the UI at present, the playground itself is an XML file that can be edited using an external text editor such as TextEdit.app.
As playgrounds can contain a mixture of code and documentation, it makes them an ideal format for viewing annotated code snippets. In fact, Apple's Swift Tour book can be opened as a playground file.
Xcode documentation can be searched by navigating to the Help | Documentation and API Reference menu, or by pressing Command + Shift + 0. In the search field that is presented, type Swift Tour and then select the first result. The Swift Tour book should be presented in Xcode's help system:
A link to download and open the documentation as a playground is given in the first section; if this is downloaded, it can...