AttributedString Markdown initializer with custom styling

AttributedString in iOS 15 and macOS 12 comes with a Markdown initializer.

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But:

• There is no styling (not even bold or italic) when drawing the AttributedString in a custom view.
• The AttributedString does have some styling applied when it’s assigned to a UILabel or to a UITextView, but they are noticeably different and weird things happen with the font sizes.
• All line breaks that should separate the content blocks are missing.
• The AttributedString colors don’t react to toggling between dark and light mode.

What’s going on?

There is not a lot of information about Markdown in AttributedString out there yet, but I think I was just holding it wrong:

The Markdown initializer merely adds semantic (not visual) markup to the AttributedString. Both UILabel and UITextView interpret these to a certain extent, while drawing a raw (NS)AttributedString doesn’t.

The Markdown initializer merely puts the Markdown parsing results as Presentation Intents into the AttributedString runs.

• There are inlinePresentationIntents, e.g. .stronglyEmphasized for bold text.
• There are presentationIntents for blocks like headlines (like .header(1) for a H1).

This sample project

This sample project shows how you can find these intents and replace them with actual AttributedString styling information like font weights and foreground colors.

I don’t know if there’s a more elegant way to solve this. Do let me know if you have a better solution!

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© 2021 Frank Rausch