With the release of iOS 6, Apple has expanded its parental controls feature to encompass iBooks content, albeit in a more limited fashion than for other types of content. While a mandatory rating system does not exist for books, options can be found under Settings, General, Restrictions to disable access to the iBookstore entirely or simply prevent the downloading of books containing explicit sexual content.
The first option allows access to the iBooks app for reading existing content while preventing users from purchasing or downloading any new iBooks directly on their device. Disabling explicit sexual content will disallow purchasing, previewing and sharing any books marked as containing explicitly sexual content—the buy and sample buttons will be disabled, no sharing link will appear, and a generic book image will be displayed in the iBookstore rather than the original book’s cover image.
With iBooks 2.2 and higher these controls will also hide any explicit books already stored on the device.