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Markup Formatting Reference

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Markup Syntax

Markup uses simple Markdown-like character delimiter syntax with custom extensions. There are four types of elements:

  • Single line elements format a line of text such as creating a heading.

  • Multiline elements format multiple lines of text such as creating lists or callouts.

  • Span elements format a span of characters such as adding emphasis.

  • Link elements add text based links such as a mailto, or inline assets such as images.

Single Line Elements

Single line elements use an opening delimiter, followed by at least one space and then the content.

  • optional spacesdelimitercontent

Single line elements follow these rules:

  • The delimiter is the first non-whitespace character on the line.

  • There is at least one space between the delimiter and the content.

  • Extra whitespace between the delimiter and content is ignored.

  • The delimiter and all of the content are be terminated by a newlin.

For example, both of the following lines of markup render as the same second level heading as shown in Figure 4-1.

  1. //: ## Second Level Heading
  2. //:   ##    Second Level Heading
Figure 4-1Headings ignoring whitespace image: ../Art/MFR_syntax_single_eg_2x.png

Link Elements

Link elements define a link name and a link target. The link name is entered between an opening square bracket ([) and a closing square bracket (]). Asset links start with an exclamation mark (!) before the opening square bracket. The target specification for the link element is usually between an opening parentheses (() and a closing parentheses ()). Link Reference delimiters use a colon (:) followed by the target specification instead of parentheses.

  • optional link type character[link name](link target  link target options)

Link elements follow these rules:

  • The link element can appear anywhere on a line.

  • The delimiter and all of the content is on one line terminated by a newline.

Example: A URL Link

The following markup renders as a link to swift.org. The link shows as clickable blue text in the rendered documentation, as shown in Figure 4-2.

  1. //: Find more information for [Swift](http://swift.org)
Figure 4-2A text link image: ../Art/MFR_syntax_link_text_eg_2x.png

Example: An Inline Image

This markup renders the image content of the link centered on the line after the word cat. The rest of the content is rendered on a line following the image as shown in Figure 4-3.

  1. //: Meet Swiftie the cat ![Swiftie the cat](cat.png) the real boss.
Figure 4-3An asset link image: ../Art/MFR_syntax_link_asset_eg_2x.png

Multiline Elements

Multiline elements such as lists and callouts use an opening delimiter, followed by at least one space and then the content. The block of content continues until meeting a termination condition.

  • delimiterline 1 content
  • optional continuation of line 1
  • optional newline
  • optional content
  • termination condition

Multiline elements follow these rules:

  • The delimiter is the first non-whitespace character on the line.

  • There is at least one space between the delimiter and the content.

  • Extra whitespace between the delimiter and content is ignored.

  • A single newline followed by text wraps the text to the previous line.

  • A single empty line followed by text inserts the text as a new paragraph.

The delimiter formats all text until one of the following termination conditions:

  • Two or more consecutive empty lines

  • A different line or multiline delimiter at the same level of nesting.

Nesting Delimiters

The nesting level of a multiline element increases for each set of four spaces or each tab preceding the opening delimiter.

Use nesting to:

  • Increase the indent level of a list

  • Add nested single line elements such as headings or horizontal rules

  • Add a Code Block

To add contiguous lines of nesting, add the same number of initial spaces or tabs on each line that starts with a delimiter. Empty lines do not need to be indented.

Example: A Simple Bulleted List

The following markup renders in Quick Help as a bulleted list with two items as shown in Figure 4-4.

  1. /**
  2.  * item 1
  3.  * item 2
  4. */
Figure 4-4Simple bulleted list image: ../Art/MFR_syntax_multi_eg_2x.png

Example: Text Wrapping

The markup below renders as a single numbered list item as shown in Figure 4-5.

  1. /*:
  2.  1. This renders as
  3.   one line in
  4.  a numbered list
  5. */
Figure 4-5Wrapping in a multiline element image: ../Art/MFR_syntax_multi_wrap_eg_2x.png

Example: Inserting a Paragraph

This markup renders Line 4 as the second paragraph in the first bullet point as shown in Figure 4-6. The content for every paragraph is indented to the same level as the containing delimiter.

  1. /**
  2.   * A bullet item
  3.     With two paragraphs
  4.   * The next bullet item
  5. */
Figure 4-6Inserting a paragraph image: ../Art/MFR_syntax_multi_para_eg_2x.png

Example: Terminating a Callout Using Two Empty Lines

The markup below renders as two different lists as shown in Figure 4-7. The first list is terminated by the two consecutive empty lines on lines 4 and 5 of the markup.

  1. /*:
  2. 1. First list, item 1
  3. 1. First list, item 2
  4. 1. Second list, item 1
  5. */
Figure 4-7Termination with empty lines image: ../Art/MFR_syntax_multi_term_lines_eg_2x.png

Example: Terminating a List with a Different Delimiter

This markup renders as two different lists, each with its own heading as shown in Figure 4-8. The heading delimiter on line 5 terminates the first list.

  1. /*:
  2. ### List A
  3. 1. Item 1, List A
  4. 1. Item 2, List A
  5. ### List B
  6. 1. Item 1, List B
  7. */
Figure 4-8Termination with a different delimiter image: ../Art/MFR_syntax_multi_term_deilm_eg_2x.png

Example: Nesting Delimiters

This markup contains three kinds of nesting as seen in Figure 4-9.

  1. The nested list is a result of adding four spaces before the delimiters for each list item on lines 3 and 8.

  2. The nested code block is a result of indenting lines 5 and 6 by twelve spaces, or two levels of indentation from the enclosing delimiter.

  3. The nested horizontal rule is a result of indenting line 7 by eight spaces or one level of indentation from the enclosing delimiter. For more information on code blocks, see Code Block.

  1. /**
  2.  1. Level 1, Item 1
  3.     1. Level 2, Item 1
  4.             func emptyFunc() {
  5.             }
  6.         - - -
  7.     1. Level 2, Item 2
  8.  1. Level 1, Item 2
  9. */
Figure 4-9Nesting image: ../Art/MFR_syntax_multi_nest_eg_2x.png

Span Elements

Span elements use the same delimiter at the start and end of the character span.

  • opening delimitercontentclosing delimiter

Span elements follow these rules:

  • The opening delimiter can appear anywhere on a line.

  • There is no space between the opening delimiter and the first character of the span.

  • There is no space between the first character and the closing delimiter of the span.

  • A single newline in the middle of a span is ignored and the text is wrapped to the first line.

  • Span elements can be combined.

Example: Ignoring Whitespace

The following markup results in one line of text as shown in Figure 4-10.

  1. /// This markup renders as one *line
  2. /// of text*
Figure 4-10Wrapping in a span element image: ../Art/MFR_syntax_span_eg_2x.png

Example: Combining Elements

This markup shows adding the delimiters for a span of bold characters inside the delimiters for a span with emphasis. The rendered result adds both emphasis and bold to inside other as seen in Figure 4-11.

  1. //: Span elements *nest **inside other** span* elements
Figure 4-11Combining span elements image: ../Art/MFR_syntax_span_nesting_eg_2x.png

Ignoring Single Newlines

Single newlines inside most line and text formatting delimiters are ignored as is whitespace at the end of a line.

For example, the following code ignores the newline at the end of Line 1, resulting in a single line of text with the words on one line rendered using the emphasis style. Adding whitespace at the end of the first line does not add spaces between the words on and one.

  1. //: This will all render *on
  2. //: one line*

Exception: Links

Markup for textual links and media assets is on a single line of text that ends in a newline. The delimiter and arguments are treated as plain text if they span multiple lines.

Delimiters for textual links begin with an open square bracket ([). Delimiters for media assets begin with an exclamation mark followed by an open square bracket (![).

For example, in the markup below the delimiter and arguments for specifying an inline video player span lines 2 and 3. All three lines are treated as plain text and wrapped together into one rendered line of text as shown in Figure 4-12.

  1. //: Watch the WWDC session introducing the San Francisco Font
  2. //: ![San Francisco font introduction]
  3. //: (new-fonts.mp4)
Figure 4-12Links don't wrap image: ../Art/MFR_video_pg_wrap_error_2x.png

Combining all the lines into one line shows the video player.