A split view manages the presentation of hierarchical content at the top level of your app. A split view consists of a two- or three-column interface showing a primary column, an optional supplementary column, and a secondary pane of content. Changes in the primary column drive changes in the optional supplementary column, which affect the content itself. Split views are useful for navigating multiple levels of content hierarchy, like traversing the mailboxes and messages in Mail to view each message.
Split views can display a variety of content, but many system apps like Mail use a split view to create a sidebar-based interface. In this type of interface, the primary column shows a sidebar, the optional supplementary column shows a list view, and the secondary content pane shows details about the selected content. For related guidance, see Sidebars.
On iPad, use a split view instead of a tab bar. Split views provide the same quick navigation as tab bars while making better use of the large display.
Choose the appropriate style for each type of column. For the primary column displaying the sidebar, use the sidebar appearance. This appearance is appropriate for app-level navigation and lists of collections, like the mailboxes in Mail. For the supplementary column displaying the list view, use the plain sidebar appearance. This appearance is appropriate for lists of individual pieces of content, like the messages in a mailbox. For developer guidance, see UICollectionLayoutListConfiguration.Appearance.
Persistently highlight the active selection in the primary and supplementary columns. Although the secondary pane's content can change, it should always correspond to clearly identifiable selections in the other columns. This selection helps people understand the relationship between the columns and keep themselves oriented.
If appropriate, allow people to drag and drop content between columns. Because split views provide access to multiple levels of hierarchy, people can quickly move content from one part of the app to another by dragging and dropping items between the columns. For related guidance, see Drag and Drop.
For developer guidance, see UISplitViewController.