A navigation bar appears at the upper edge of an application screen, just below the status bar.
A navigation bar usually displays the title of the current screen or view, centered along its length.
A navigation bar enables navigation through an information hierarchy and, optionally, management of screen contents.
A navigation bar can be translucent or opaque.
On iPhone, a navigation bar always displays across the full width of the screen.
On iPad, a navigation bar can display within a view, such as one pane of a split view, that does not extend across the screen.
Use the title of the current view as the title of the navigation bar.
When the user navigates to a new level, two things should happen:
- The bar title should change to the new level’s title.
- A back button should appear to the left of the title, and it should be labeled with the previous level’s title.
Use a toolbar instead of a navigation bar if you need to offer a larger set of controls, or you do not need to enable navigation.
Consider putting a segmented control in a navigation bar at the top level of an application.
Avoid crowding a navigation bar with additional controls, even if there appears to be enough space.
Use system-provided buttons according to their documented meaning.
If appropriate, customize the appearance of a navigation bar.
Make sure that a customized back button still looks like a back button.
Don’t create a multisegment back button.
On iPhone, take into account the automatic change in navigation bar height that occurs on device rotation.