Swift-DocC

Swift-DocC is a documentation compiler for Swift frameworks and packages aimed at making it easy to write and publish great developer documentation.

For an example of Swift-DocC in action, check out developer.apple.com. Much of Apple's developer documentation, from Reference documentation to Tutorials, is built using Swift-DocC.

Swift-DocC is being actively developed. For more information about the Swift-DocC project, see the introductory blog post here.

The latest documentation for the Swift-DocC project is available on Swift.org.

The Swift Forums are the best place to get help with Swift-DocC and discuss future plans.

Writing and Publishing Documentation with Swift-DocC

If you're looking to write and publish documentation with Swift-DocC, the best way to get started is with Swift-DocC's user documentation.

Technical Overview and Related Projects

Swift-DocC builds documentation by combining Symbol Graph files containing API information with a .docc Documentation Catalog containing articles and tutorials to create a final archive containing the compiled documentation.

More concretely, Swift-DocC understands the following kinds of inputs:

1. Symbol Graph files with the .symbols.json extension. Symbol Graph files are a machine-readable representation of a module's APIs, including their documentation comments and relationship with one another.

2. A Documentation Catalog with the .docc extension. Documentation Catalogs can include additional documentation content like the following:

   • Documentation markup files with the .md extension. Documentation markup files can be used to extend documentation for symbols and to write free-form articles.

   • Tutorial files with the .tutorial extension. Tutorial files are used to author step-by-step instructions on how to use a framework.

   • Additional documentation assets with known extensions like .png, .jpg, .mov, and .zip.

   • An Info.plist file containing metadata such as the name of the documented module. This file is optional and the information it contains can be passed via the command line.

Swift-DocC outputs a machine-readable archive of the compiled documentation. This archive contains render JSON files, which fully describe the contents of a documentation page and can be processed by a renderer such as Swift-DocC-Render.

For more in-depth technical information about Swift-DocC, you can build and preview the project's technical documentation from the command line with

bin/preview-docs

Note: The preview-docs script expects the DOCC_HTML_DIR environment variable to be set with the path to a Swift-DocC renderer. See the Using docc to build and preview documentation section below for details.

Alternatively, you can open the package in Xcode 13 and select the "Build Documentation" button in the Product menu to view the documentation in Xcode's documentation window.

Related Projects

• As of Swift 5.5, the Swift Compiler is able to emit Symbol Graph files as part of the compilation process.

• SymbolKit is a Swift package containing the specification and reference model for the Symbol Graph File Format.

• Swift Markdown is a Swift package for parsing, building, editing, and analyzing Markdown documents. It includes support for the Block Directive elements that Swift-DocC's tutorial files rely on.

• Swift-DocC-Render is a web application that understands and renders Swift-DocC's render JSON format.

• Xcode consists of a suite of tools that developers use to build apps for Apple platforms. Beginning with Xcode 13, Swift-DocC is integrated into Xcode with support for building and viewing documentation for your framework and its dependencies.

Getting Started with docc

docc is the command line interface (CLI) for Swift-DocC and provides support for converting and previewing DocC documentation.

Prerequisites

DocC is a Swift package. If you're new to Swift package manager, the documentation here provides an explanation of how to get started and the software you'll need installed.

DocC requires Swift 5.5 which is included in Xcode 13.

Build

1. Checkout this repository using:

   git clone https://github.com/apple/swift-docc.git

2. Navigate to the root of the repository with:

   cd swift-docc

3. Finally, build DocC by running:

   swift build

Run

To run docc, run the following command:

swift run docc

Installing into Xcode

You can test a locally built version of Swift-DocC in Xcode 13 or later by setting the DOCC_EXEC build setting to the path of your local docc:

1. Select the project in the Project Navigator.

2. In the Build Settings tab, click '+' and then 'Add User-Defined Setting'.

3. Create a build setting DOCC_EXEC with the value set to /path/to/docc.

The next time you invoke a documentation build with the "Build Documentation" button in Xcode's Product menu, your custom docc will be used for the build. You can confirm that your custom docc is being used by opening the latest build log in Xcode's report navigator and expanding the "Compile documentation" step.

Using docc to build and preview documentation

You can use docc directly to build documentation for your Swift framework or package. The below instructions use this repository as an example but apply to any Swift package. Just replace any reference to SwiftDocC below with the name of your package.

1. Generate a symbol graph file

Begin by navigating to the root of your Swift package.

cd ~/Developer/swift-docc

Then run the following to generate Symbol Graph files for your target:

mkdir -p .build/symbol-graphs && \
  swift build --target SwiftDocC \
    -Xswiftc -emit-symbol-graph \
    -Xswiftc -emit-symbol-graph-dir -Xswiftc .build/symbol-graphs

You should now have a number of .symbols.json files in .build/symbol-graphs representing the provided target and its dependencies. You can copy out the files representing just the target itself with:

mkdir .build/swift-docc-symbol-graphs \
  && mv .build/symbol-graphs/SwiftDocC* .build/swift-docc-symbol-graphs

2. Set the path to your renderer

The best place to get started with Swift-DocC-Render is with the instructions in the project's README.

If you have Xcode 13 or later installed, you can use the version of Swift-DocC-Render that comes included in Xcode with:

export DOCC_HTML_DIR="$(dirname $(xcrun --find docc))/../share/docc/render"

Alternatively, you can clone the Swift-DocC-Render-Artifact repository and use a recent pre-built copy of the renderer:

git clone https://github.com/apple/swift-docc-render-artifact.git

Then point the DOCC_HTML_DIR environment variable to the repository's /dist folder.

export DOCC_HTML_DIR="/path/to/swift-docc-render-artifact/dist"

3. Preview your documentation

The docc preview command performs a conversion of your documentation and starts a local web server to allow for easy previewing of the built documentation. It monitors the provided Documentation Catalog for changes and updates the preview as you're working.

docc preview Sources/SwiftDocC/SwiftDocC.docc \
  --fallback-display-name SwiftDocC \
  --fallback-bundle-identifier org.swift.SwiftDocC \
  --fallback-bundle-version 1.0.0 \
  --additional-symbol-graph-dir .build/swift-docc-symbol-graphs

You should now see the following in your terminal:

Input: ~/Developer/swift-docc/Sources/SwiftDocC/SwiftDocC.docc
Template: ~/Developer/swift-docc-render-artifact/dist
========================================
Starting Local Preview Server
   Address: http://localhost:8000/documentation/swiftdocc
========================================
Monitoring ~/Developer/swift-docc/Sources/SwiftDocC/SwiftDocC.docc for changes...

And if you navigate to http://localhost:8000/documentation/swiftdocc you'll see the rendered documentation for SwiftDocC.

Versioning

Swift-DocC's CLI tool (docc) will be integrated into the Swift toolchain and follows the Swift compiler's versioning scheme.

The SwiftDocC library is versioned separately from docc. SwiftDocC is under active development and source stability is not guaranteed.

Bug Reports and Feature Requests

Submitting a Bug Report

Swift-DocC tracks all bug reports with Swift JIRA. When you submit a bug report we ask that you follow the Swift Bug Reporting guidelines and provide as many details as possible.

Note: You can use the environment script in this repository to gather helpful environment information to paste into your bug report by running the following:

bin/environment

If you can confirm that the bug occurs when using the latest commit of Swift-DocC from the main branch (see Building Swift-DocC), that will help us track down the bug faster.

Submitting a Feature Request

For feature requests, please feel free to create an issue on Swift JIRA with the New Feature type or start a discussion on the Swift Forums.

Don't hesitate to submit a feature request if you see a way Swift-DocC can be improved to better meet your needs.

All user-facing features must be discussed in the Swift Forums before being enabled by default.

Contributing to Swift-DocC

Please see the contributing guide for more information.