Action Sheets
An action sheet is a specific style of alert that appears in response to a control or action, and presents a set of two or more choices related to the current context. Use an action sheet to let people initiate tasks, or to request confirmation before performing a potentially destructive operation. On smaller screens, an action sheet slides up from the bottom of the screen. On larger screens, an action sheet appears all at once as a popover.
Provide a Cancel button if it adds clarity. A Cancel button instills confidence when the user is abandoning a task. Cancel buttons should always be included in action sheets at the bottom of the screen.
Make destructive choices prominent. Use red for buttons that perform destructive or dangerous actions, and display these buttons at the top of an action sheet.
Avoid enabling scrolling in an action sheet. If an action sheet has too many options, people must scroll to see all of the choices. Scrolling requires extra time to make a choice and is hard to do without inadvertently tapping a button.
For implementation details, see the UIAlertControllerStyleActionSheet constant in UIAlertController.