markdownSourcePosition

Declaration

let markdownSourcePosition: AttributeScopes.FoundationAttributes.MarkdownSourcePositionAttribute

Discussion

This attribute indicates the position in the Markdown source where a run of attributed text begins and ends, omitting markup characters in the source. For example, after parsing the source string “This is *emphasized*.”, the text emphasized has a Markdown source position that starts at column 10. This index is the “e” character, not the “*” formatting character.

An attributed string parsed from Markdown text includes this attribute only if the appliesSourcePositionAttributes value in the AttributedString.MarkdownParsingOptions provided to the AttributedString initializer is true.

In the following example, the markdown source string contains several forms of Markdown formatting supported by AttributedString, including the stronglyEmphasized inline presentation intent applied with double asterisks. The example parses the source string, enabling the appliesSourcePositionAttributes option. Next, the example loops over the attributed string’s runs, looking for a run that contains both a markdownSourcePosition attribute and an inlinePresentationIntent whose value is stronglyEmphasized. If it finds such a run, it prints the source position attribute and the attributed text.

let markdown = "Examples of *emphasis*, **strong emphasis**, and [link](https://example.com)."
let options = AttributedString.MarkdownParsingOptions(appliesSourcePositionAttributes: true)
if let attString = try? AttributedString(markdown: markdown, options: options) {
    for run in attString.runs {
        if let sourcePosition = run.markdownSourcePosition,
           let sourceRange = Range(sourcePosition, in: markdown),
           let presentationIntent = run.inlinePresentationIntent,
           presentationIntent.contains(.stronglyEmphasized) {
               print("Found strong emphasis: \(sourcePosition), text: '\(markdown[sourceRange])'")
        }
    }
}
// Prints: Found strong emphasis: MarkdownSourcePosition(startLine: 1, startColumn: 27, endLine: 1, endColumn: 41, startOffsets: Optional(Foundation.AttributedString.MarkdownSourcePosition.Offsets(utf8: 26, utf16: 26, utf8NextCodePoint: 27, utf16CurrentCodePointLength: 1)), endOffsets: Optional(Foundation.AttributedString.MarkdownSourcePosition.Offsets(utf8: 40, utf16: 40, utf8NextCodePoint: 41, utf16CurrentCodePointLength: 1))), text: 'strong emphasis'

This uses the Range convenience initializer init(_:in:), which creates a range from an AttributedString.MarkdownSourcePosition and the Markdown source string. Working with a range may be more convenient than working with the start and end position properties in AttributedString.MarkdownSourcePosition.

See Also

Using Markdown source position attributes

• AttributeScopes.FoundationAttributes.MarkdownSourcePositionAttribute