Earlier today, Apple's senior writer Dave Addey fired off a tweet announcing the company's "iOS Human Interface Guidelines" is now available to grab from the iBookstore. The download is free and available for anyone who wants it.
Oddly enough, the publication date is listed as March 10, but Addey assures that it was released today. Previously, the guidelines could only be accessed online through Apple's developer portal. With the conversion to iBooks comes a sleek alternative option.
The iOS Human Interface Guidelines book details Apple's various guidelines and design principles, helping developers create a solid user experience. With the iBooks version comes integrated annotations, reading adjustment settings, and more.
There's also two-page layout options and inline video playback, as well. In order to grab the book, developers will need an iOS mobile with iBooks 1.5 or later and iOS 4.3.3 or higher, or a Mac running iBooks 1.0 or later and OS X 10.9 or higher.