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https://github.com/SimonFairbairn/SwiftyMarkdown

Converts Markdown files and strings into NSAttributedStrings with lots of customisation options.
https://github.com/SimonFairbairn/SwiftyMarkdown

character-styles formatting markdown markdown-converter

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Converts Markdown files and strings into NSAttributedStrings with lots of customisation options.

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README 

        
# SwiftyMarkdown 1.0



SwiftyMarkdown converts Markdown files and strings into `NSAttributedString`s using sensible defaults and a Swift-style syntax. It uses dynamic type to set the font size correctly with whatever font you'd like to use.



- [What's New](#fully-rebuilt-for-2020)

- [Installation](#installation)

- [How to Use](#how-to-use-swiftymarkdown)

- [Screenshot](#screenshot)

- [Front Matter](#front-matter)

- [Appendix](#appendix)



## Fully Rebuilt For 2020!



SwiftyMarkdown now features a more robust and reliable rules-based line processing and character tokenisation engine. It has added support for images stored in the bundle (`![Image]()`), codeblocks, blockquotes, and unordered lists!



Line-level attributes can now have a paragraph alignment applied to them (e.g. `h2.aligment = .center`), and links can be optionally underlined by setting `underlineLinks` to `true`. 



It also uses the system color `.label` as the default font color on iOS 13 and above for Dark Mode support out of the box. 



Support for all of Apple's platforms has been enabled.



## Installation



### CocoaPods:



`pod 'SwiftyMarkdown'`



### SPM: 



In Xcode, `File -> Swift Packages -> Add Package Dependency` and add the GitHub URL. 



## How To Use SwiftyMarkdown



Read Markdown from a text string...



```swift

let md = SwiftyMarkdown(string: "# Heading\nMy *Markdown* string")

md.attributedString()

```



...or from a URL.



```swift

if let url = Bundle.main.url(forResource: "file", withExtension: "md"), md = SwiftyMarkdown(url: url ) {

	md.attributedString()

}

```



If you want to use a different string once SwiftyMarkdown has been initialised, you can now do so like this:



```swift

let md = SwiftyMarkdown(string: "# Heading\nMy *Markdown* string")

md.attributedString(from: "A **SECOND** Markdown string. *Fancy!*")

```



The attributed string can then be assigned to any label or text control that has support for attributed text. 



```swift

let md = SwiftyMarkdown(string: "# Heading\nMy *Markdown* string")

let label = UILabel()

label.attributedText = md.attributedString()

```



## Supported Markdown Features



    *italics* or _italics_

    **bold** or __bold__

    ~~Linethrough~~Strikethroughs. 

    `code`



    # Header 1



	or



    Header 1

    ====



    ## Header 2



	or



    Header 2

    ---



    ### Header 3

    #### Header 4

    ##### Header 5 #####

    ###### Header 6 ######



		Indented code blocks (spaces or tabs)



    [Links](http://voyagetravelapps.com/)

    ![Images]()

    

    [Referenced Links][1]

    ![Referenced Images][2]

    

    [1]: http://voyagetravelapps.com/

    [2]: 

    

    > Blockquotes

	

	- Bulleted

	- Lists

		- Including indented lists

			- Up to three levels

	- Neat!

	

	1. Ordered

	1. Lists

		1. Including indented lists

			- Up to three levels



	

		

Compound rules also work, for example:

		

	It recognises **[Bold Links](http://voyagetravelapps.com/)**

	

	Or [**Bold Links**](http://voyagetravelapps.com/)



Images will be inserted into the returned `NSAttributedString` as an `NSTextAttachment` (sadly, this will not work on watchOS as `NSTextAttachment` is not available). 



## Customisation 



Set the attributes of every paragraph and character style type using straightforward dot syntax:



```swift

md.body.fontName = "AvenirNextCondensed-Medium"



md.h1.color = UIColor.redColor()

md.h1.fontName = "AvenirNextCondensed-Bold"

md.h1.fontSize = 16

md.h1.alignmnent = .center



md.italic.color = UIColor.blueColor()



md.underlineLinks = true



md.bullet = "🍏"

```



On iOS, Specified font sizes will be adjusted relative to the the user's dynamic type settings.



## Screenshot



![Screenshot](https://cl.ly/779e6964257a/swiftymarkdown-2020.png)



There's an example project included in the repository. Open the `Example/SwiftyMarkdown.xcodeproj` file to get started.



## Front Matter



SwiftyMarkdown recognises YAML front matter and will populate the `frontMatterAttributes` property with the key-value pairs that it fines. 



## Appendix 



### A) All Customisable Properties 



```swift

h1.fontName : String

h1.fontSize : CGFloat

h1.color : UI/NSColor

h1.fontStyle : FontStyle

h1.alignment : NSTextAlignment



h2.fontName : String

h2.fontSize : CGFloat

h2.color : UI/NSColor

h2.fontStyle : FontStyle

h2.alignment : NSTextAlignment



h3.fontName : String

h3.fontSize : CGFloat

h3.color : UI/NSColor

h3.fontStyle : FontStyle

h3.alignment : NSTextAlignment



h4.fontName : String

h4.fontSize : CGFloat

h4.color : UI/NSColor

h4.fontStyle : FontStyle

h4.alignment : NSTextAlignment



h5.fontName : String

h5.fontSize : CGFloat

h5.color : UI/NSColor

h5.fontStyle : FontStyle

h5.alignment : NSTextAlignment



h6.fontName : String

h6.fontSize : CGFloat

h6.color : UI/NSColor

h6.fontStyle : FontStyle

h6.alignment : NSTextAlignment



body.fontName : String

body.fontSize : CGFloat

body.color : UI/NSColor

body.fontStyle : FontStyle

body.alignment : NSTextAlignment



blockquotes.fontName : String

blockquotes.fontSize : CGFloat

blockquotes.color : UI/NSColor

blockquotes.fontStyle : FontStyle

blockquotes.alignment : NSTextAlignment



link.fontName : String

link.fontSize : CGFloat

link.color : UI/NSColor

link.fontStyle : FontStyle



bold.fontName : String

bold.fontSize : CGFloat

bold.color : UI/NSColor

bold.fontStyle : FontStyle



italic.fontName : String

italic.fontSize : CGFloat

italic.color : UI/NSColor

italic.fontStyle : FontStyle



code.fontName : String

code.fontSize : CGFloat

code.color : UI/NSColor

code.fontStyle : FontStyle



strikethrough.fontName : String

strikethrough.fontSize : CGFloat

strikethrough.color : UI/NSColor

strikethrough.fontStyle : FontStyle



underlineLinks : Bool



bullet : String

```



`FontStyle` is an enum with these cases: `normal`, `bold`, `italic`, and `bolditalic` to give you more precise control over how lines and character styles should look. For example, perhaps you want blockquotes to default to having the italic style:



```swift

md.blockquotes.fontStyle = .italic

```

Or, if you like a bit of chaos:



```swift

md.bold.fontStyle = .italic

md.italic.fontStyle = .bold

```



### B) Advanced Customisation



SwiftyMarkdown uses a rules-based line processing and customisation engine that is no longer limited to Markdown. Rules are processed in order, from top to bottom. Line processing happens first, then character styles are applied based on the character rules. 



For example, here's how a small subset of Markdown line tags are set up within SwiftyMarkdown:



```swift

enum MarkdownLineStyle : LineStyling {

	case h1

	case h2

	case previousH1

	case codeblock

	case body

	

	var shouldTokeniseLine: Bool {

		switch self {

		case .codeblock:

			return false

		default:

			return true

		}

	}

	

	func styleIfFoundStyleAffectsPreviousLine() -> LineStyling? {

		switch self {

		case .previousH1:

			return MarkdownLineStyle.h1

		default :

			return nil

		}

	}

}



static public var lineRules = [

	LineRule(token: "    ",type : MarkdownLineStyle.codeblock, removeFrom: .leading),

	LineRule(token: "=",type : MarkdownLineStyle.previousH1, removeFrom: .entireLine, changeAppliesTo: .previous),

	LineRule(token: "## ",type : MarkdownLineStyle.h2, removeFrom: .both),

	LineRule(token: "# ",type : MarkdownLineStyle.h1, removeFrom: .both)

]



let lineProcessor = SwiftyLineProcessor(rules: SwiftyMarkdown.lineRules, default: MarkdownLineStyle.body)

```



Similarly, the character styles all follow rules:



```swift

enum CharacterStyle : CharacterStyling {

	case link, bold, italic, code

}



static public var characterRules = [

    CharacterRule(primaryTag: CharacterRuleTag(tag: "[", type: .open), otherTags: [

			CharacterRuleTag(tag: "]", type: .close),

			CharacterRuleTag(tag: "[", type: .metadataOpen),

			CharacterRuleTag(tag: "]", type: .metadataClose)

	], styles: [1 : CharacterStyle.link], metadataLookup: true, definesBoundary: true),

	CharacterRule(primaryTag: CharacterRuleTag(tag: "`", type: .repeating), otherTags: [], styles: [1 : CharacterStyle.code], shouldCancelRemainingTags: true, balancedTags: true),

	CharacterRule(primaryTag: CharacterRuleTag(tag: "*", type: .repeating), otherTags: [], styles: [1 : CharacterStyle.italic, 2 : CharacterStyle.bold], minTags:1 , maxTags:2),

	CharacterRule(primaryTag: CharacterRuleTag(tag: "_", type: .repeating), otherTags: [], styles: [1 : CharacterStyle.italic, 2 : CharacterStyle.bold], minTags:1 , maxTags:2)

]

```



These Character Rules are defined by SwiftyMarkdown:



	public struct CharacterRule : CustomStringConvertible {



		public let primaryTag : CharacterRuleTag

		public let tags : [CharacterRuleTag]

		public let escapeCharacters : [Character]

		public let styles : [Int : CharacterStyling]

		public let minTags : Int

		public let maxTags : Int

		public var metadataLookup : Bool = false

		public var definesBoundary = false

		public var shouldCancelRemainingRules = false

		public var balancedTags = false

	}



1. `primaryTag`: Each rule must have at least one tag and it can be one of `repeating`, `open`, `close`, `metadataOpen`, or `metadataClose`. `repeating` tags are tags that have identical open and close characters (and often have more than 1 style depending on how many are in a group). For example, the `*` tag used in Markdown.

2. `tags`: An array of other tags that the rule can look for. This is where you would put the `close` tag for a custom rule, for example.

3. `escapeCharacters`: The characters that appear prior to any of the tag characters that tell the scanner to ignore the tag. 

4. `styles`: The styles that should be applied to every character between the opening and closing tags. 

5. `minTags`: The minimum number of repeating characters to be considered a successful match. For example, setting the `primaryTag` to `*` and the `minTag` to 2 would mean that `**foo**` would be a successful match wheras `*bar*` would not.

6. `maxTags`: The maximum number of repeating characters to be considered a successful match. 

7. `metadataLookup`: Used for Markdown reference links. Tells the scanner to try to look up the metadata from this dictionary, rather than from the inline result. 

8. `definesBoundary`: In order for open and close tags to be successful, the `boundaryCount` for a given location in the string needs to be the same. Setting this property to `true` means that this rule will increase the `boundaryCount` for every character between its opening and closing tags. For example, the `[` rule defines a boundary. After it is applied, the string `*foo[bar*]` becomes `*foobar*` with a boundaryCount `00001111`. Applying the `*` rule results in the output `*foobar*` because the opening `*` tag and the closing `*` tag now have different `boundaryCount` values. It's basically a way to fix the `**[should not be bold**](url)` problem in Markdown. 

9. `shouldCancelRemainingTags`: A successful match will mark every character between the opening and closing tags as complete, thereby preventing any further rules from being applied to those characters.

10. `balancedTags`: This flag requires that the opening and closing tags be of exactly equal length. E.g. If this is set to true,  `**foo*` would result in `**foo*`. If it was false, the output would be `*foo`.



#### Rule Subsets



If you want to only support a small subset of Markdown, it's now easy to do. 



This example would only process strings with `*` and `_` characters, ignoring links, images, code, and all line-level attributes (headings, blockquotes, etc.)

```swift

SwiftyMarkdown.lineRules = []



SwiftyMarkdown.characterRules = [

	CharacterRule(primaryTag: CharacterRuleTag(tag: "*", type: .repeating), otherTags: [], styles: [1 : CharacterStyle.italic, 2 : CharacterStyle.bold], minTags:1 , maxTags:2),

	CharacterRule(primaryTag: CharacterRuleTag(tag: "_", type: .repeating), otherTags: [], styles: [1 : CharacterStyle.italic, 2 : CharacterStyle.bold], minTags:1 , maxTags:2)

]

```



#### Custom Rules



If you wanted to create a rule that applied a style of `Elf` to a range of characters between "The elf will speak now: %Here is my elf speaking%", you could set things up like this:



```swift

enum Characters : CharacterStyling {

	case elf



	func isEqualTo( _ other : CharacterStyling) -> Bool {

		if let other = other as? Characters else {

			return false

		}

		return other == self

	}

}



let characterRules = [

	CharacterRule(primaryTag: CharacterRuleTag(tag: "%", type: .repeating), otherTags: [], styles: [1 : CharacterStyle.elf])

]



let processor = SwiftyTokeniser( with : characterRules )

let string = "The elf will speak now: %Here is my elf speaking%"

let tokens = processor.process(string)

```



The output is an array of tokens would be equivalent to:



```swift

[

	Token(type: .string, inputString: "The elf will speak now: ", characterStyles: []),

	Token(type: .repeatingTag, inputString: "%", characterStyles: []),

	Token(type: .string, inputString: "Here is my elf speaking", characterStyles: [.elf]),

	Token(type: .repeatingTag, inputString: "%", characterStyles: [])

]

```



### C) SpriteKit Support



Did you know that `SKLabelNode` supports attributed text? I didn't.



```swift

let smd = SwiftyMarkdown(string: "My Character's **Dialogue**")



let label = SKLabelNode()

label.preferredMaxLayoutWidth = 500

label.numberOfLines = 0

label.attributedText = smd.attributedString()

```