Refresh Content Controls
A refresh control is manually initiated to immediately reload content, typically in a table view, without waiting for the next automatic content update to occur. A refresh control is a specialized type of activity indicator, is hidden by default, and becomes visible when dragging down on the view to be reloaded. In Mail, for example, you can drag the list of Inbox messages down to check for new messages.
Perform automatic content updates. Although people appreciate being able to trigger an immediate content refresh, they also expect automatic refreshes to occur periodically. Don’t make users responsible for initiating every update. Keep data fresh by updating it regularly.
Supply a short title only if it adds value. Optionally, a refresh control can include a title. In most cases, this is unnecessary, as the animation of the control indicates that content is loading. If you do include a title, don’t use it to explain how to perform a refresh. Instead, provide information of value about the content being refreshed. A refresh control in Podcasts, for example, uses a title to tell people when the last podcast update occurred.
For developer guidance, see UIRefreshControl.