A segmented control is a linear set of two or more segments, each of which functions as a mutually exclusive button. Within the control, all segments are equal in width. Like buttons, segments can contain text or images. Segmented controls are often used to display different views. In Maps, for example, a segmented control lets you switch between Map, Transit, and Satellite views.
Limit the number of segments to improve usability. Wider segments are easier to tap. On iPhone, a segmented control should have five or fewer segments.
Try to keep segment content size consistent. Because all segments have equal width, it doesn’t look great if content fills some segments but not others.
Avoid mixing text and images in a segmented control. Although individual segments can contain text or images, mixing the two in a single control can lead to a disconnected and confusing interface.
Position content appropriately in a custom a segmented control. If you change the background appearance of a segmented control, make sure content still looks good and doesn’t appear misaligned.
For developer guidance, see UISegmentedControl.