CODEWITHSUNDEEP
iosrtfnsattributedstring
Benjohn
Benjohn

Reputation: 13887

NSAttributedString from RTF using iOS Dynamic-Type

My App has a simple built in help page. The page is loaded from a rich-text file in to an NSAttributedString, and the string is displayed in a UITextView.

Here's a fragment of code from prepareForSegue: where I load the NSAttributedString prior to using it for display…

NSURL *const textURL =
[[NSBundle mainBundle] URLForResource: @"DontPanic"
                        withExtension: @"rtf"];

NSDictionary *const options =
@{NSDocumentTypeDocumentAttribute: NSRTFTextDocumentType};

NSAttributedString *const text =
[[NSAttributedString alloc] initWithURL: textURL
                                options: options
                     documentAttributes: nil
                                  error: nil];

This all works well. However, it doesn't support iOS's "Dynamic Type" – the fonts are baked in to the RTF file and don't react to the users's settings.

I'd like the guide to use the system defined styles for body: UIFontTextStyleBody and heading: UIFontTextStyleHeadline.

How might I do this?

I'd be fairly happy for the guide to be defined in another format such as HTML or Markdown. I'd prefer not to add external libraries to the project if I can avoid them, though.

Upvotes: 3

Views: 637

Answers (1)

beyowulf
beyowulf

Reputation: 15331

You have access to preferred fonts through CSS. For example you could create an html document like:

<html>
    <body>
        <h1 style="font: -apple-system-headine; font-family:-apple-system;">My heading</h1>
        <p style ="font: -apple-system-body; font-family:-apple-system;">The body of this document</p>
    </body>
</html>

Then replace NSRTFTextDocumentType with NSHTMLTextDocumentType in the code you have above.

The full list of preferred font names in CSS is:

-apple-system-headline
-apple-system-subheadline
-apple-system-short-headline
-apple-system-short-subheadline
-apple-system-body
-apple-system-short-body
-apple-system-tall-body
-apple-system-caption1
-apple-system-caption2
-apple-system-short-caption1
-apple-system-footnote
-apple-system-short-footnote

If you don't want to define the fonts on every element, you can modify the styling in the html <head> tag like this:

<html>
  <head>
    <style type="text/css">
      H1 {font: -apple-system-headine; font-family: -apple-system;}
      P {font: -apple-system-body; font-family: -apple-system;}
    </style>
  </head>

  <body>
    <h1>This is a heading. It will be shown with the dynamic type headline font.</h1>
    <p>This is a paragraph. It will use the dynamic type body font.</p>
  </body>
</html>

Upvotes: 3

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