Dialogs inform users about a task and can contain critical information, require decisions, or involve multiple tasks.
To display a modal using MaterialDialogs you set two properties on the view controller to be presented. Set modalPresentationStyle to UIModalPresentationCustom and set transitioningDelegate to and instance of MDCDialogTransitionController. Then you present the view controller from the root controller to display it as a modal dialog.
Presenting dialogs uses two classes: MDCDialogPresentationController and MDCDialogTransitionController. These allow the presentation of view controllers in a material specificed manner. MDCDialogPresentationController is a subclass of UIPresentationController that observes the presented view controller for preferred content size. MDCDialogTransitionController implements UIViewControllerAnimatedTransitioning and UIViewControllerTransitioningDelegate to vend the presentation controller during the transition.
MDCAlertController provides a simple interface for developers to present a modal dialog according to the Material spec.