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A command-line tool and Swift Package for generating class diagrams powered by PlantUML


Generate UML class diagrams from swift code with this Command Line Interface (CLI) and Swift Package.

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Use one or more Swift files as input for a diagram to visualize class, struct, protocol, enum and extension types with their instance and static members as well as their inheritance and implementation relationships

Example Diagram

Table of Contents (click to expand)


Command Line

Example to generate and render diagram, based on a single Swift file, in your browser:

swiftplantuml ./Tests/SwiftPlantUMLFrameworkTests/TestData/basics.txt

Run swiftplantuml in the directory containing the Swift files to be considered for diagram generation. Directories will be searched recursively.

$ swiftplantuml classdiagram --help
OVERVIEW: Generate PlantUML script and view it and diagram in browser

USAGE: swift-plant-uml classdiagram [--config <config>] [--exclude <exclude> ...] [--output <format>] [--sdk <sdk>] [--verbose] [<paths> ...]

  <paths>                 List of paths to the files or directories containing
                          swift sources

  --config <config>       Path to custom configuration filed (otherwise will
                          search for `.swiftplantuml.yml` in current directory)
  --exclude <exclude>     paths to ignore source files. Takes precedence over
  --output <format>       Defines output format. Options: browser,
                          browserImageOnly, consoleOnly
  --sdk <sdk>             MacOSX SDK path used to handle type inference
                          resolution, usually `$(xcrun --show-sdk-path -sdk
  --verbose               Verbose
  --version               Show the version.
  -h, --help              Show help information.

As classdiagram is the default subcommand you can omit it.

Note: unknown type in diagrams for variables declared with type inference (e.g. var hasBasket = false) unless you specify sdk argument

Type inference details (click to expand)

In the following example the property hasBasket is of type Bool but the type is inferred and not explicitly declared.

class Bicycle: Vehicle {
    var hasBasket = false

SwiftPlantUML requires the macosx SDK in order to properly recognize the inferred type. If you have Xcode installed (which includes the macosx SDK) then use --sdk $(xcrun --show-sdk-path -sdk macosx).

No inferred type (default) inferred type
Generated PlantUML ~hasBasket ~hasBasket : Bool
Command swiftplantuml classdiagram Tests/SwiftPlantUMLFrameworkTests/TestData/demo.txt swiftplantuml classdiagram Tests/SwiftPlantUMLFrameworkTests/TestData/demo.txt --sdk $(xcrun --show-sdk-path -sdk macosx)

Swift package

dependencies: [
    .package(url: "https://github.com/MarcoEidinger/SwiftPlantUML.git", .upToNextMajor(from: "0.3.0"))

This project is still in initial development. Generally this anything may change at any time and the public API should not be considered stable). However, I'll try to reserve breaking changes for new minor versions. You might feel more comfortable to pin the version to .upToNextMinor or even to an .exact version.

API documentation

Xcode source editor extension

See MarcoEidinger/SwiftPlantUML-Xcode-Extension for more details


Using Homebrew

brew install MarcoEidinger/formulae/swiftplantuml

Using Mint

$ mint install MarcoEidinger/SwiftPlantUML

Installing from source

You can also build and install from source by cloning this project and running make install (Xcode 12 or later).

Manually Run the following commands to build and install manually:

$ git clone https://github.com/MarcoEidinger/SwiftPlantUML.git
$ cd SwiftPlantUML
$ make install


Configure SwiftPlantUML by adding a .swiftplantuml.yml file from the directory you'll run SwiftPlantUML from. Note: the same configuration options can be set programmatically with Configuration.


You are able to

  • include/exclude files (wildcards supported)
  • include/exclude elements by name (wildcards supported)
  • limit elements and members bases on their access level, e.g. show only public types
  • hide extensions
  • hide member access level attribute
  • configure styles, use skin parameters and even include external files for theming (e.g. PUML Themes)
  • exclude inheritance relationships based on parent (wildcards supported), e.g. do not show inheritance to Codable


Simple Example:

    - "Tests/**/*.swift" # paths to ignore for diagram. Takes precedence over `included`.
  - public
  - public
  showExtensions: false
skinparamCommands: # see https://plantuml.com/skinparam
- skinparam classBackgroundColor PaleGreen
- skinparam classArrowColor SeaGreen
- skinparam classBorderColor SpringGreen
- skinparam stereotypeCBackgroundColor YellowGreen
- skinparam stereotypeCBackgroundColor<< Foo >> DimGray
    label: "inherits from"
      lineStyle: dotted
      lineColor: DarkViolet
      textColor: DarkViolet
    - "Codable"

Rich example: here

Code Completion during Editing


To get code completiong during editing use Visual Studio Code, the YAML extension created by Red Hat and the JSON schema for SwiftPlantUML.

In Visual Studio Code: Code -> Preferences -> Settings -> search for yaml

Screen Shot 2021-02-27 at 5 57 49 AM

Click on Edit in settings.json and add the respective entry:

"yaml.schemas": {"https://raw.githubusercontent.com/MarcoEidinger/SwiftPlantUML/main/Configuration/Schema/json-schema-swiftplantuml.json": "/.swiftplantuml.yml" }

Planned improvements

  • being able to render associations between elements
  • being able to merge extensions with their known type

Known limitations

  • huge diagrams in browser
    • PlantUML limits image width and height to 4096 with the option to override this limit when using PlantUML.jar. locally so your option is to use the --textonlyoption and adjust/use it with PlantUML tools directly


This project was inspired by https://github.com/palaniraja and its various predecessors. Out of personal preference I chose to start a new project. I wanted to provide a tool for Swift developers written in Swift! This will hopefully allow me and potential contributors to work on planned improvements faster and more efficient.

Last but not least a big shoutout to the great developers of PlantUML and the people who operate the related online servers / tools available on http://plantuml.com/ and https://www.planttext.com/


Stars: 25
Last commit: 15 hours ago


- 2021-03-01T03:19:29

0.3.0 (2021-02-28)


  • 🎸 show inferred type (if SDK path was provided) (107f8b6), closes #14
  • 🎸 various configuration options with .swiftplantuml.yml (6bb08f3), closes #9 and #10

Bug Fixes

  • 🐛 multiple file paths handled incorrectly #12