jazzy is a command-line utility that generates documentation for Swift or Objective-C

About

Both Swift and Objective-C projects are supported.

Instead of parsing your source files, jazzy hooks into Clang and SourceKit to use the AST representation of your code and its comments for more accurate results. The output matches the look and feel of Apple’s official reference documentation, post WWDC 2014.

Jazzy can also generate documentation from compiled Swift modules using their symbol graph instead of source code.

This project adheres to the Contributor Covenant Code of Conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to info@realm.io.

Requirements

You need development tools to build the project you wish to document. Jazzy supports both Xcode and Swift Package Manager projects.

Jazzy expects to be running on macOS. See below for tips to run Jazzy on Linux.

Installation

[sudo] gem install jazzy

See Installation Problems for solutions to some common problems.

Usage

Run jazzy from your command line. Run jazzy -h for a list of additional options.

If your Swift module is the first thing to build, and it builds fine when running xcodebuild or swift build without any arguments from the root of your project, then just running jazzy (without any arguments) from the root of your project should succeed too!

If Jazzy generates docs for the wrong module then use --module to tell it which one you'd prefer. If this doesn't help, and you're using Xcode, then try passing extra arguments to xcodebuild, for example jazzy --build-tool-arguments -scheme,MyScheme,-target,MyTarget.

You can set options for your project’s documentation in a configuration file, .jazzy.yaml by default. For a detailed explanation and an exhaustive list of all available options, run jazzy --help config.

Supported documentation keywords

Swift documentation is written in markdown and supports a number of special keywords. Here are some resources with tutorials and examples, starting with the most modern:

• Apple's Writing Symbol Documentation in Your Source Files article.
• Apple's Formatting Your Documentation Content article.
• Apple's Xcode Markup Formatting Reference.
• Erica Sadun's Swift header documentation in Xcode 7 post and her book on Swift Documentation Markup.

For Objective-C documentation the same keywords are supported, but note that the format is slightly different. In Swift you would write - returns:, but in Objective-C you write @return. See Apple's HeaderDoc User Guide for more details. Note: jazzy currently does not support all Objective-C keywords listed in this document, only @param, @return, @warning, @see, @note, @code, @endcode, and @c.

Jazzy can also generate cross-references within your documentation. A symbol name in backticks generates a link, for example:

• `MyClass` - a link to documentation for MyClass.
• `MyClass.method(param1:)` - a link to documentation for that method.
• `MyClass.method(...)` - shortcut syntax for the same thing.
• `method(...)` - shortcut syntax to link to method from the documentation of another method or property in the same class.
• `[MyClass method1]` - a link to an Objective-C method.
• `-[MyClass method2:param1]` - a link to another Objective-C method.

Jazzy understands Apple's DocC-style links too, for example:

• ``MyClass/method(param1:)`` - a link to the documentation for that method that appears as just method(param1:) in the rendered page.
• ``<doc:method(_:)-e873>`` - a link to a specific overload of method(_:). Jazzy can't tell which overload you intend and links to the first one.

Math

Jazzy can render math equations written in LaTeX embedded in your markdown:

• `$equation$` renders the equation in an inline style.
• `$$equation$$` renders the equation in a display style, centered on a line of its own.

For example, the markdown:

Inline: `$ax^2+bx+c=0$`

Block: `$$x={\frac {-b\pm {\sqrt {b^{2}-4ac}}}{2a}}$$`

..renders as:

Math support is provided by KaTeX.

Swift

Swift documentation is generated by default.

Example

This is how Realm Swift docs are generated:

jazzy \
  --clean \
  --author Realm \
  --author_url https://realm.io \
  --source-host github \
  --source-host-url https://github.com/realm/realm-cocoa \
  --source-host-files-url https://github.com/realm/realm-cocoa/tree/v0.96.2 \
  --module-version 0.96.2 \
  --build-tool-arguments -scheme,RealmSwift \
  --module RealmSwift \
  --root-url https://realm.io/docs/swift/0.96.2/api/ \
  --output docs/swift_output \
  --theme docs/themes

This is how docs are generated for a project that uses the Swift Package Manager:

jazzy \
  --module DeckOfPlayingCards \
  --swift-build-tool spm \
  --build-tool-arguments -Xswiftc,-swift-version,-Xswiftc,5

Objective-C

To generate documentation for a simple Objective-C project, you must pass the following parameters:

• --objc
• --umbrella-header ...
• --framework-root ...

...and optionally:

• --sdk [iphone|watch|appletv][os|simulator]|macosx (default value of macosx)
• --hide-declarations [objc|swift] (hides the selected language declarations)

For example, this is how the AFNetworking docs are generated:

jazzy \
  --objc \
  --author AFNetworking \
  --author_url http://afnetworking.com \
  --source-host github \
  --source-host-url https://github.com/AFNetworking/AFNetworking \
  --source-host-files-url https://github.com/AFNetworking/AFNetworking/tree/2.6.2 \
  --module-version 2.6.2 \
  --umbrella-header AFNetworking/AFNetworking.h \
  --framework-root . \
  --module AFNetworking

For a more complicated Objective-C project, instead use --build-tool-arguments to pass arbitrary compiler flags. For example, this is how Realm Objective-C docs are generated:

jazzy \
  --objc \
  --clean \
  --author Realm \
  --author_url https://realm.io \
  --source-host github \
  --source-host-url https://github.com/realm/realm-cocoa \
  --source-host-files-url https://github.com/realm/realm-cocoa/tree/v2.2.0 \
  --module-version 2.2.0 \
  --build-tool-arguments --objc,Realm/Realm.h,--,-x,objective-c,-isysroot,$(xcrun --show-sdk-path),-I,$(pwd) \
  --module Realm \
  --root-url https://realm.io/docs/objc/2.2.0/api/ \
  --output docs/objc_output \
  --head "$(cat docs/custom_head.html)"

See the Objective-C docs for more information and some tips on troubleshooting.

Mixed Objective-C / Swift

This feature is new and has some rough edges.

To generate documentation for a mixed Swift and Objective-C project you must first generate two SourceKitten files: one for Swift and one for Objective-C.

Then pass these files to Jazzy together using --sourcekitten-sourcefile.

Example

This is how docs are generated from an Xcode project for a module containing both Swift and Objective-C files:

# Generate Swift SourceKitten output
sourcekitten doc -- -workspace MyProject.xcworkspace -scheme MyScheme > swiftDoc.json

# Generate Objective-C SourceKitten output
sourcekitten doc --objc $(pwd)/MyProject/MyProject.h \
      -- -x objective-c  -isysroot $(xcrun --show-sdk-path --sdk iphonesimulator) \
      -I $(pwd) -fmodules > objcDoc.json

# Feed both outputs to Jazzy as a comma-separated list
jazzy --module MyProject --sourcekitten-sourcefile swiftDoc.json,objcDoc.json

Docs from .swiftmodules or frameworks

This feature is new: there may be crashes and mistakes. Reports welcome.

Swift 5.3 added support for symbol graph generation from .swiftmodule files.

Jazzy can use this to generate API documentation. This is faster than using the source code directly but does have limitations: for example documentation comments are available only for public declarations, and the presentation of Swift extensions may not match the way they are written in code.

Some examples:

1. Generate docs for the Apple Combine framework for macOS:

   jazzy --module Combine --swift-build-tool symbolgraph

   The SDK's library directories are included in the search path by default.
2. Same but for iOS:

   jazzy --module Combine --swift-build-tool symbolgraph
         --sdk iphoneos
         --build-tool-arguments -target,arm64-apple-ios14.1

   The target is the LLVM target triple and needs to match the SDK. The default here is the target of the host system that Jazzy is running on, something like x86_64-apple-darwin19.6.0.
3. Generate docs for a personal .swiftmodule:

   jazzy --module MyMod --swift-build-tool symbolgraph
         --build-tool-arguments -I,/Build/Products

   This implies that /Build/Products/MyMod.swiftmodule exists. Jazzy's --source-directory (default current directory) is searched by default, so you only need the -I override if that's not enough.
4. For a personal framework:

   jazzy --module MyMod --swift-build-tool symbolgraph
         --build-tool-arguments -F,/Build/Products

   This implies that /Build/Products/MyMod.framework exists and contains a .swiftmodule. Again the --source-directory is searched by default if -F is not passed in.
5. With pre-generated symbolgraph files:

   jazzy --module MyMod --swift-build-tool symbolgraph
         --symbolgraph-directory Build/symbolgraphs

   If you've separately generated symbolgraph files by the use of -emit-symbol-graph, you can pass the location of these files using --symbolgraph-directory from where they can be parsed directly.

See swift symbolgraph-extract -help for all the things you can pass via --build-tool-arguments: if your module has dependencies then you may need to add various search path options to let Swift load it.

Themes

Three themes are provided with jazzy: apple (default), fullwidth and jony.

• apple example: https://realm.io/docs/swift/latest/api/
• fullwidth example: https://reduxkit.github.io/ReduxKit/
• jony example: https://harshilshah.github.io/IGListKit/

You can specify which theme to use by passing in the --theme option. You can also provide your own custom theme by passing in the path to your theme directory.

Guides

By default, jazzy looks for one of README.md, README.markdown, README.mdown or README (in that order) in the directory from where it runs to render the index page at the root of the docs output directory. Using the --documentation option, extra markdown files can be integrated into the generated docs and sidebar navigation.

Any files found matching the file pattern will be parsed and included as a document with the type 'Guide' when generated. If the files are not included using the custom_categories config option, they will be grouped under 'Other Guides' in the sidebar navigation.

There are a few limitations:

• File names must be unique from source files.
• Readme should be specified separately using the readme option.

Section description abstracts

Using the --abstract options, extra markdown can be included after the heading of section overview pages. Think of it as a template include.

The list of files matching the pattern is compared against the list of sections generated and if a match is found, it's contents will be included in that section before listing source output.

Unlike the --documentation option, these files are not included in navigation and if a file does not match a section title, it is not included at all.

This is very helpful when using custom_categories for grouping types and including relevant documentation in those sections.

For an example of a project using both --documentation and --abstract see: https://reswift.github.io/ReSwift/

Controlling what is documented

In Swift mode, Jazzy by default documents only public and open declarations. To include declarations with a lower access level, set the --min-acl flag to internal, fileprivate, or private.

By default, Jazzy does not document declarations marked @_spi when --min-acl is set to public or open. Set the --include-spi-declarations flag to include them.

In Objective-C mode, Jazzy documents all declarations found in the --umbrella-header header file and any other header files included by it.

You can control exactly which declarations should be documented using --exclude, --include, or :nodoc:.

The --include and --exclude flags list source files that should be included/excluded respectively in the documentation. Entries in the list can be absolute pathnames beginning with / or relative pathnames. Relative pathnames are interpreted relative to the directory from where you run jazzy or, if the flags are set in the config file, relative to the directory containing the config file. Entries in the list can match multiple files using * to match any number of characters including /. For example:

• jazzy --include=/Users/fred/project/Sources/Secret.swift -- include a specific file
• jazzy --exclude=/*/Internal* -- exclude all files with names that begin with Internal and any files under any directory with a name beginning Internal.
• jazzy --exclude=Impl1/*,Impl2/* -- exclude all files under the directories Impl1 and Impl2 found in the current directory.

Note that the --include option is applied before the --exclude option. For example:

• jazzy --include=/*/Internal* --exclude=Impl1/*,Impl2/* -- include all files with names that begin with Internal and any files under any directory with a name beginning Internal, except for those under the directories Impl1 and Impl2 found in the current directory

Declarations with a documentation comment containing :nodoc: are excluded from the documentation.

Documentation structure

Jazzy arranges documentation into categories. The default categories are things like Classes and Structures corresponding to programming-language concepts, as well as Guides if --documentation is set.

You can customize the categories and their contents using custom_categories in the config file — see the ReSwift docs and config file for an example.

Within each category the items are ordered first alphabetically by source filename, and then by declaration order within the file. You can use // MARK: comments within the file to create subheadings on the page, for example to split up properties and methods. There’s no way to customize this order short of editing either the generated web page or the SourceKitten JSON.

Swift extensions and Objective-C categories allow type members to be declared across multiple source files. In general, extensions follow the main type declaration: first extensions from the same source file, then extensions from other files ordered alphabetically by filename. Swift conditional extensions (extension A where …) always appear beneath unconditional extensions.

Use this pattern to add or customize the subheading before extension members:

extension MyType {
  // MARK: Subheading for this group of methods
  …
}

When Jazzy is using --swift-build-tool symgraph the source file names and line numbers may not be available. In this case the ordering is approximately alphabetical by symbol name and USR; the order is stable for the same input.

Jazzy does not normally create separate web pages for declarations that do not have any members -- instead they are entirely nested into their parent page. Use the --separate-global-declarations flag to change this and create pages for these empty types.

Choosing the Swift language version

Jazzy normally uses the Swift compiler from the Xcode currently configured by xcode-select. Use the --swift-version flag or the DEVELOPER_DIR environment variable to compile with a different Xcode.

The value you pass to --swift-version must be the Swift language version given by swift --version in the Xcode you want to use. Jazzy uses xcinvoke to find a suitable Xcode installation on your system. This can be slow: if you know where Xcode is installed then it's faster to set DEVELOPER_DIR directly.

For example to use Xcode 14:

jazzy --swift-version 5.7

...or:

DEVELOPER_DIR=/Applications/Xcode_14.app/Contents/Developer jazzy

Linux

Jazzy uses SourceKitten to communicate with the Swift build environment and compiler. The sourcekitten binary included in the Jazzy gem is built for macOS and so does not run on other operating systems.

To use Jazzy on Linux you first need to install and build sourcekitten following instructions from SourceKitten's GitHub repository.

Then to generate documentation for a SwiftPM project, instead of running just jazzy do:

sourcekitten doc --spm > doc.json
jazzy --sourcekitten-sourcefile doc.json

We hope to improve this process in the future.

Troubleshooting

Swift

Only extensions are listed in the documentation?

Check the --min-acl setting -- see above.

Unable to find an Xcode with swift version X

1. The value passed with --swift-version must exactly match the version number from swiftc --version. For example Xcode 10.1 needs --swift-version 4.2.1. See the flag documentation.
2. The Xcode you want to use must be in the Spotlight index. You can check this using mdfind 'kMDItemCFBundleIdentifier == com.apple.dt.Xcode'. Some users have reported this issue being fixed by a reboot; mdutil -E may also help. If none of these work then you can set the DEVELOPER_DIR environment variable to point to the Xcode you want before running Jazzy without the --swift-version flag.

Objective-C

See this document.

Miscellaneous

Missing docset

Jazzy only builds a docset when you set the --module flag.

Unable to pass --build-tool-arguments containing commas

If you want Jazzy to run something like xcodebuild -scheme Scheme -destination 'a=x,b=y,c=z' then you must use the config file instead of the CLI flag because the CLI parser that Jazzy uses cannot handle arguments that themselves contain commas.

The example config file here would be:

build_tool_arguments:
  - "-scheme"
  - "Scheme"
  - "-destination"
  - "a=x,b=y,c=z"

Errors running in an Xcode Run Script phase

Running Jazzy from an Xcode build phase can go wrong in cryptic ways when Jazzy has to run xcodebuild.

Users have reported that error messages about symbols lacking USRs can be fixed by unsetting LLVM_TARGET_TRIPLE_SUFFIX as part of the run script.

Installation Problems

Can't find header files / clang

Some of the Ruby gems that Jazzy depends on have native C extensions. This means you need the Xcode command-line developer tools installed to build them: run xcode-select --install to install the tools.

/Applications/Xcode: No such file or directory

The path of your active Xcode installation must not contain spaces. So /Applications/Xcode.app/ is fine, /Applications/Xcode-10.2.app/ is fine, but /Applications/Xcode 10.2.app/ is not. This restriction applies only when installing Jazzy, not running it.

MacOS Before 10.14.4

Starting with Jazzy 0.10.0, if you see an error similar to dyld: Symbol not found: _$s11SubSequenceSlTl then you need to install the Swift 5 Runtime Support for Command Line Tools.

Alternatively, you can:

• Update to macOS 10.14.4 or later; or
• Install Xcode 10.2 or later at /Applications/Xcode.app.

Development

Please review jazzy's contributing guidelines when submitting pull requests.

jazzy is composed of two parts:

1. The parser, SourceKitten (written in Swift)
2. The site generator (written in ruby)

To build and run jazzy from source:

1. Install bundler.
2. Run bundle install from the root of this repo.
3. Run jazzy from source by running bin/jazzy.

Instructions to build SourceKitten from source can be found at SourceKitten's GitHub repository.

Design Goals

• Generate source code docs matching Apple's official reference documentation
• Support for standard Objective-C and Swift documentation comment syntax
• Leverage modern HTML templating (Mustache)
• Leverage the power and accuracy of the Clang AST and SourceKit
• Support for Dash docsets
• Support Swift and Objective-C

License

This project is released under the MIT license.

About

Jazzy is maintained and funded by Realm Inc. The names and logos for Realm are trademarks of Realm Inc.

We ❤️ open source software! See our other open source projects, read our blog or say hi on twitter (@realm).