Not only has the Apple's iBooks store recently recorded 1 billion e-book downloads since its launch, the online e-book seller is also attracting a 1 million new users a week and sells e-books in 51 countries, said iBooks store director Keith Moerer during an onstage intervew at DBW.

Moerer credited most of the iBooks store continuing growth to the launch of iOS 8, which now includes the iBooks Store/App pre-installed. "It's made it really easy for new users to try it out and download a free book," he said. Moerer also pointed to the release of the iPhone 6 and 6+ with bigger screens and high-res retina display, "which are particularly great for reading."

While Apple does not specifically track reading on its devices, Moerer said more e-book sales are coming from iPhones. Though he did not provide figures, he said self-publishing also continues to grow, crediting Apple's history of "working with creative professional." But he also emphasized that the iBooks Store is completlely "editorially driven, there's no pay to play, no coop payments or pay for placement."

Book discovery, he said, is driven through both the homepages and "lots of traffic via category pages." "We also help authors sell outside of the iBooks store with live events at our Apple stores," and using email and twitter chats.

Genre fiction, movie tie-ins (cross promoted through movie sales via iTunes), memoir and health are big sellers and he cited working with Smashwords to distribute self-published romance.

Illustrated books and children's titles are slow but growing, he said. On the foreign market, the U.K., Germany and France "have robust sales,"while Japanese language is the fastest growing market. "Latin America is slower but gaining momentum."

Moerer also said that the iBooks store's pricing policies helped attract self-publishing, particularly the ability to give books away for free as promotions. "Indie authors often give away the first book in a series. We're happy to distribute free content. It helps us attract customers and turn them into paying customers," he said.