Описание тега uialertcontroller
An iOS class, for displaying alerts and popup style selectors. Note that the legacy `UIActionSheet` and `UIAlertView` tags would not generally be used now.
In iOS, UIAlertController displays an alert message to the user, or, an action selector. (On iPhone, it's the large selector which appears from the bottom of the screen, usually with two or three choices.)
After configuration, it is presented using UIViewController.present. In the action sheet case, actions are added using UIAlertController.addAction.
This class replaced the older UIActionSheet and UIAlertView.