I use the Kindle app on my iPad for quilt books I purchase or check out digitally from the library (as well as quilting magazines I check out digitally from the library). I borrowed Angela Walters book Free Motion Meandering from the library, then opened it it split screen with my Notes app in the other half of the screen. That allowed me to practice drawing the designs using my Pencil with the book open to the appropriate page.
But I still like flipping through my print books when I am looking for inspiration.