A Swift package for working with GraphViz.

• Swift 5.2+
• GraphViz

import GraphViz

var graph = Graph(directed: true)

let a = Node("a"), b = Node("b"), c = Node("c")

graph.append(Edge(from: a, to: b))
graph.append(Edge(from: a, to: c))

var b_c = Edge(from: b, to: c)
b_c.constraint = false
graph.append(b_c)

// Render image to SVG using dot layout algorithm
graph.render(using: .dot, to: .svg) { result in 
  guard .success(let data) = result,
        let svg = String(data: data, encoding: .utf8)
  else { return }

  print(svg)
}

digraph {
  a -> b
  a -> c
  b -> c [constraint=false]
}

Note: render(using:to:) and related methods require GraphViz to be installed on your system.

import GraphViz

let graph = Graph(directed: true) {
    "a" --> "b"
    "a" --> "c"
    ("b" --> "c").constraint(false)
}

Note: Swift 5.1 may require explicit typecast expressions in order to reconcile use of custom edge operators like -->. (error: ambiguous reference to member '-->')

You can install GraphViz on your system by running the following command:

# macOS
$ brew install graphviz

# Linux (Ubuntu)
$ sudo apt-get install graphviz

Important: If you add GraphViz to your macOS app and installed system dependencies using Homebrew, Xcode may emit an error message like the following:

Warning: Could not load "/usr/lib/graphviz/libgvplugin_gdk.so.6"
It was found, so perhaps one of its dependents was not. Try ldd.

One solution is to run the following commands to sign the dependencies (replacing MyName (MyTeam) with your developer account name and team name):

$ codesign -f -s "Apple Development: MyName (MyTeam)" /usr/local/opt/*/lib/*.dylib
$ codesign -f -s "Apple Development: MyName (MyTeam)" /usr/local/Cellar/*/*/lib/*.dylib

Add the GraphViz package to your target dependencies in Package.swift:

import PackageDescription

let package = Package(
  name: "YourProject",
  dependencies: [
    .package(
        url: "https://github.com/SwiftDocOrg/GraphViz",
        from: "0.4.1"
    ),
  ]
)

Add GraphViz as a dependency to your target(s):

targets: [
.target(
    name: "YourTarget",
    dependencies: ["GraphViz"]),

MIT

Mattt (@mattt)