Besides displaying data or letting users input data, the second most important purpose of a user interface is to allow users to control an app. At the simplest level, users can use buttons where each button represents a single command. Of course if you want to display multiple options, displaying multiple buttons on the screen can get crowded.
For two alternatives for giving commands, Xcode offers switches and segmented controls. A switch lets users choose to turn a setting on or off. A segmented control acts like multiple buttons, in a condensed area, ...
