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Alex Rupérez

Published: 11 Jan 16:18
I starred danger/swift at GitHub.
⚠️ Stop saying "you forgot to …" in code review in Swift
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Formalize your Pull Request etiquette.

Write your Dangerfiles in Swift 4+.


Latest version requires Swift 4.2

  • If you are using Swift 4.1 use v0.4.1
  • If you are using Swift 4.0, Use v0.3.6

Because this project recommends homebrew right now, this only works with the most recent version of danger-swift. Ideally we'll document how to use swiftpm to version danger correctly.

What it looks like today

You can make a Dangerfile that looks through PR metadata, it's fully typed.

import Danger

let danger = Danger()
let allSourceFiles = danger.git.modifiedFiles + danger.git.createdFiles

let changelogChanged = allSourceFiles.contains("")
let sourceChanges = allSourceFiles.first(where: { $0.hasPrefix("Sources") })

if !changelogChanged && sourceChanges != nil {
  warn("No CHANGELOG entry added.")

// You can use these functions to send feedback:
message("Highlight something in the table")
warn("Something pretty bad, but not important enough to fail the build")
fail("Something that must be changed")

markdown("Free-form markdown that goes under the table, so you can do whatever.")

Getting Started

Using Danger in Swift

  1. Install Danger Swift: brew install danger/tap/danger-swift.
  2. Edit the dangerfile: danger-swift edit.

This will make a Dangerfile.swift for you. then pop up a temporary Xcode project set up for editing a Swift Dangerfile.


Full documentation is available here.


  • danger-swift ci - Use this on CI
  • danger-swift pr - Use this to build your Dangerfile
  • danger-swift local - Use this to run danger against your local changes from master
  • danger-swift edit - Creates a temporary Xcode project for working on a Dangerfile


Infrastructure exists to support plugins, which can help you avoid repeating the same Danger rules across separate repos. By suffixing package: [url] to an import, you can directly import Swift PM package as a dependency(through Marathon).

For example, a plugin could be used by the following.

// Dangerfile.swift

import DangerPlugin // package:


And could be implemented with the following in that repo.

// DangerPlugin.swift
import Danger

public struct DangerPlugin {
    static let danger = Danger()
    public static func doYourThing() {
        // Code goes here

You can see an example danger-swift plugin.


For a Mac:

# Install danger-swift, and a bundled danger-js locally
brew install danger/tap/danger-swift  
 # Run danger
danger-swift ci

For Linux:

# Install danger-swift
git clone
cd danger-swift
make install

# Install danger-js
npm install -g danger

 # Run danger
danger-swift ci

With Docker support ready for GitHub Actions.

What are the next big steps?

How it works

This project takes its ideas from how the Swift Package Manager handles package manifests. You can get the long story here, but the TLDR is that there is a runner project which compiles and executes a runtime lib which exports its data out into JSON when the libs process is over.

So this project will export a lib libDanger and a CLI tool danger-swift which is the runner. danger-swift handles turning the Danger DSL JSON message from DangerJS and passing that into the eval'd Dangerfile.swift. When that process is finished it's expected that the Swift Danger object would post the results into a place where they can easily be passed back to DangerJS.


You need to be using Xcode 10.

git clone
cd danger-swift
swift build
swift run komondor install
swift package generate-xcodeproj
open Danger.xcodeproj

Then I tend to run danger-swift using swift run:

swift run danger-swift pr

If you want to emulate how DangerJS's process will work entirely, then use:

swift build && cat Fixtures/eidolon_609.json | ./.build/debug/danger-swift


Run swift run rocket $VERSION on master e.g. swift run rocket 1.0.0


I, orta, only plan on bootstrapping this project, as I won't be using this in production. I'm happy to help support others who want to own this idea and really make it shine though! So if you're interested in helping out, make a few PRs and I'll give you org access.