They use this class

These are a (non-exhaustive) list of projects that are known to use OHAttributedLabel

• Food Reporter — (AppStore | WebSite EN | WebSite FR) — by @AliSoftware (me)
• Weave
• SmartQuiz
• Roadside America by @jdandrea (This Exit LLC)
• Dashr by Torpedo Apps
• Timeable by Ryleigh Kostash
• Line2 by Toktumi, Inc.
• phonetrait by Paul Steinhilber : Calling poeple with style
• Regex Live! by Rockhold Company, LLC
• iWill XT & iWill HD by Sud Soft System
• Ants (Ants Carpooling) by Ants Labs
• Klikt by Muzlak LLC
• Frankenstein (and other books) by Inkle

(And many more)

Feel free to let me know if you use OHAttributedLabel in your projects so I can add your project in the list and we can cross-reference.