CommonMark

import CommonMark

let markdown = #"""
# [Universal Declaration of Human Rights][udhr]

## Article 1.

All human beings are born free and equal in dignity and rights. 
They are endowed with reason and conscience 
and should act towards one another in a spirit of brotherhood.

[udhr]: https://www.un.org/en/universal-declaration-human-rights/ "View full version"
"""#

let document = try Document(markdown)

document.children.count // 3

let heading = document.children[0] as! Heading
heading.headerLevel // 1
heading.children.count // 1

let link = heading.children[0] as! Link
link.urlString // "https://www.un.org/en/universal-declaration-human-rights/")
link.title // "View full version"

let subheading = document.children[1] as! Heading
subheading.headerLevel // 2
subheading.children.count // 1

let subheadingText = subheading.children[0] as! Text
subheadingText.literal // "Article 1."

let paragraph = document.children[2] as! Paragraph
paragraph.description // "All human beings [ ... ]"
paragraph.range.lowerBound // (line: 5, column: 1)
paragraph.range.upperBound // (line: 7, column: 62)

let html = document.render(format: .html) // <h1> [ ... ]
let xml = document.render(format: .xml) // <?xml [ ... ]
let latex = document.render(format: .latex) // \section{ [ ... ]
let manpage = document.render(format: .manpage) // .SH [ ... ]

// To get back CommonMark text, 
// you can either render with the `.commonmark` format...
document.render(format: .commonmark) // # [Universal  [ ... ]
// ...or call `description`
// (individual nodes also return their CommonMark representation as their description)
document.description // # [Universal  [ ... ]

import CommonMark

let document = Document {
    Heading {
        Link(urlString: "https://www.un.org/en/universal-declaration-human-rights/",
                title: "View full version")
        {
            "Universal Declaration of Human Rights"
        }
    }

    Section { // sections increase the level of contained headings
        Heading { "Article 1." } // this is a second-level heading
    }

    // block-level strings are parsed as CommonMark literals
    """
    **All** human beings are born free and equal in dignity and rights.
    They are endowed with reason and conscience
    and should act towards one another in a spirit of brotherhood.
    """
}

let link = Link(urlString: "https://www.un.org/en/universal-declaration-human-rights/",
                title: "View full version", 
                text: "Universal Declaration of Human Rights")
let heading = Heading(level: 1, children: [link])

let subheading = Heading(level: 2, text: "Article 1.")

let paragraph = Paragraph(children: #"""
All human beings are born free and equal in dignity and rights.
They are endowed with reason and conscience
and should act towards one another in a spirit of brotherhood.
"""#.split(separator: "\n")
    .flatMap { [Text(String($0)), SoftLineBreak()] })

Document(children: [heading, subheading, paragraph]).description == document.description // true

import PackageDescription

let package = Package(
  name: "YourProject",
  dependencies: [
    .package(
        url: "https://github.com/SwiftDocOrg/CommonMark",
        from: "0.5.1"
    ),
  ]
)