isCancel property

Marks the action as the cancel button.

Maps to UIAlertAction.Style.cancel, which UIKit positions itself regardless of where the action sits in the list.

At most one action in a call may set this: UIKit raises NSInternalInconsistencyException when a second .cancel action is added, which is a crash, not a layout quirk.

Unlike a plain dismissal, a cancel action still reports its value — an alert cannot be dismissed by tapping outside, so pressing cancel is a deliberate answer and the caller is told about it.