A page control shows the position of the current page in a flat list of pages. It appears as a series of small indicator dots, representing the available pages in the order they were opened. A solid dot denotes the current page. Visually, these dots are always equidistant, and are clipped if too many appear onscreen.
A page control itself is a noninteractive element intended for informational purposes only. It doesn’t actually serve as a means of navigation—for example, you can’t click a dot to go to a specific page.
Use page controls on collections of full-screen pages. A page control is designed to operate in a full-screen environment where multiple content-rich pages are peers in the page hierarchy. Inclusion of additional controls makes it difficult to maintain focus while moving between pages.
Don’t display too many pages. More than about 10 dots are hard to count at a glance, and more than about 20 open pages are time-consuming to visit in sequence. If your app needs to display more than 20 pages as peers, consider using a different arrangement—such as a grid—that enables nonsequential navigation.
For developer guidance, see UIPageControl.