PresentationController

An object that manages the transition animations and the presentation of view controllers onscreen.

open class PresentationController 

Initializers

init(presentedViewController:presenting:)

Initializes and returns a presentation controller for transitioning between the specified view controllers

public init(presentedViewController: ViewController,
              presenting presentingViewController: ViewController?) 

This method is the designated initializer for the presentation controller. You must call it from any custom initialization methods you define for your presentation controller subclasses.

Properties

delegate

The delegate object for managing adaptive presentations.

open weak var delegate: AdaptivePresentationControllerDelegate?

When the application’s size changes, the presentation controller works with this delegate object to determine an appropriate response. View controllers presented using the ModalPresentationStyle.formSheet, ModalPresentationStyle.popover, or ModalPresentationStyle.custom style must change to use one of the full-screen presentation styles instead. The delegate can also opt to change the presented view controller entirely.

The object you assign to this property must conform to the AdaptivePresentationControllerDelegate protocol.

presentingViewController

The view controller that is the starting point for the presentation.

open private(set) var presentingViewController: ViewController

The object in this property could be the root view controller of the window, a parent view controller that is marked as defining the current context, or the last view controller that was presented onscreen. This view controller may or may not be the same one whose present(_:animated:completion:) method was called to initiate the presentation process. It may also not be the view controller used to initialize your presentation controller.

presentedViewController

The view controller being presented.

open private(set) var presentedViewController: ViewController

This object corresponds to the one passed as the first parameter of the present(_:animated:completion:) method. The successful conclusion of the presentation process causes this view controller’s content to be displayed onscreen.

containerView

The view in which the presentation occurs.

open private(set) var containerView: View?

The framework sets the value of this property shortly after receiving the presentation controller from your transitioning delegate. The container view is always an ancestor of the presented view controller’s view. During transition animations, the container view also contains the presenting view controller’s view. When adding custom views to a presentation, add them to the container view.

If your transition also employs custom animator objects, those objects can get this container view from the containerView property of the context object provided by the framework.

presentedView

The view to be animated by the animator objects during a transition.

open private(set) var presentedView: View?

The default implementation of this method returns the presented view controller’s view. If you want to animate a different view, you may override this method and return that view. The view you specify must either be the presented view controller’s view or must be one of its ancestors.

The view returned by this method is given to the animator objects, which are responsible for animating it onscreen. The animator objects retrieve the view using the view(forKey:) method of the context object provided by the framework.

The framework calls this method multiple times during the course of a presentation, so your implementation should return the appropriate view as quickly as possible. Do not use this method to actually configure your view hierarchy. If you intend to return a custom view, configure your view hierarchy in the presentationTransitionWillBegin() method.

frameOfPresentedViewInContainerView

The frame rectangle to assign to the presented view at the end of the animations.

open var frameOfPresentedViewInContainerView: Rect

The default implementation of this method returns the frame rectangle of the container view, which results in the presented view controller’s content occupying the entire presentation space. You can override this method and return a different frame rectangle as needed. For example, you might specify a smaller frame rectangle if you want some of the underlying content to show around the edges of the presented view.

The framework calls this method multiple times during the course of a presentation, so your implementation should return the same frame rectangle each time. Do not use this method to make changes to your view hierarchy or perform other one-time tasks.

overrideTraitCollection

Interface traits for the presented view controller, to use in place of traits from the current device environment.

open var overrideTraitCollection: TraitCollection?

Use this property to provide an interface trait collection for the presented view controller, overriding one or more values in the current device trait environment.

Each value you place in the overrideTraitCollection property overrides the corresponding value in the current device trait environment. For example, the following code snippet shows how to override the display scale for the presented view controller, leaving other traits as they are provided by the system. Place such code, typically, in the implementation file for the presenting view controller:

viewController.presentationController.overrideTraitCollection = TraitCollection(traitsFrom: [.current, .init(displayScale: 1.5)])
self.present(viewController, animated: false, completion: nil)

The presenting view controller is not affected by use of this property.

The default value of the overrideTraitCollection property is nil, which results in the full current device trait environment being used by the presented view controller.

presentationStyle

The presentation style of the presented view controller.

open private(set) var presentationStyle: ModalPresentationStyle

This property is set to the presentation style of the presented view controller. The presentation controller uses this style to determine the initial appearance of the presented content.

adaptivePresentationStyle

Returns the presentation style to use when the presented view controller becomes horizontally compact.

@available(*, unavailable)
  open var adaptivePresentationStyle: ModalPresentationStyle = .none

After the content managed by the presentation controller is onscreen, this method returns the presentation style to use when transitioning to a horizontally compact environment. This method is not meant to be overridden. The implementation consults its delegate object and returns the value provided by that object’s adaptivePresentationStyle(for:) method. Some system-supplied presentation controllers may also provide a new style that is more suited for a compact environment. For example, presentation controllers that manage popovers and form sheets return the ModalPresentationStyle.fullScreen value.

This method only returns the presentation style to use in a horizontally compact environment. It does not initiate a transition to the new style. The system initiates the transition to the new style when the size class actually changes. When transitioning to a new style, the actual presentation controller object may change. As a result, do not cache the presentation controller object in your code. Always retrieve it from your view controller’s presentationController property.

Use adaptivePresentationStyle(for:) instead.

shouldPresentInFullscreen

A boolean value indicating whether the presentation covers the entire screen.

open private(set) var shouldPresentInFullscreen: Bool = true

The default implementation of this method returns true, indicating that the presentation covers the entire screen. You can override this method and return false to force the presentation to display only in the current context.

If you override this method, do not call super.

shouldRemovePresentersView

A boolean value indicating whether the presenting view controller’s view should be removed when the presentation animations finish.

open private(set) var shouldRemovePresentersView: Bool = false

The default implementation of this method returns false. If you implement a presentation that does not cover the presenting view controller’s content entirely, override this method and return false.

If you override this method, do not call super.

Methods

containerViewWillLayoutSubviews()

Notifies the presentation controller that layout is about to begin on the views of the container view.

open func containerViewWillLayoutSubviews() 

The framework calls this method before adjusting the layout of the views in the container view. Use this method and the containerViewDidLayoutSubviews() method to update any custom views managed by your presentation controller.

containerViewDidLayoutSubviews()

Called to notify the presentation controller that layout ended on the views of the container view.

open func containerViewDidLayoutSubviews() 

The framework calls this method after adjusting the layout of the views in the container view. Use this method to make any additional changes to the view hierarchy.

presentationTransitionWillBegin()

Notifies the presentation controller that the presentation animations are about to start.

open func presentationTransitionWillBegin() 

The default implementation of this method does nothing. Subclasses can override it and use it to add custom views to the view hierarchy and to create any animations associated with those views. To perform your animations, get the transition coordinator of the presented view controller and call its animate(alongsideTransition:completion:) or animateAlongsideTransition(in:animation:completion:) method. Calling those methods ensures that your animations are executed at the same time as any other transition animations.

presentationTransitionDidEnd(_:)

Notifies the presentation controller that the presentation animations finished.

open func presentationTransitionDidEnd(_ completed: Bool) 

The default implementation of this method does nothing. Subclasses can override this method and use it to perform any required cleanup. For example, if the completed parameter is false, you would use this method to remove your presentation’s custom views from the view hierarchy.

dismissalTransitionWillBegin()

Notifies the presentation controller that the dismissal animations are about to start.

open func dismissalTransitionWillBegin() 

The default implementation of this method does nothing. Subclasses can override this method and use it to configure any animations associated with your presentation’s custom views. To perform your animations, get the transition coordinator of the presented view controller and call its animate(alongsideTransition:completion:) or animateAlongsideTransition(in:animation:completion:) method. Calling those methods ensures that your animations are executed at the same time as any other transition animations.

Do not use this method to remove your views from the view hierarchy. Remove your views in the dismissalTransitionDidEnd(_:) method instead.

dismissalTransitionDidEnd(_:)

Notifies the presentation controller that the dismissal animations finished.

open func dismissalTransitionDidEnd(_ completed: Bool) 

The default implementation of this method does nothing. Subclasses can override this method and use it to remove any custom views that the presentation controller added to the view hierarchy. Remove your views only if the completed parameter is true.

adaptivePresentationStyle(for:)

Returns the presentation style to use for the specified set of traits.

open func adaptivePresentationStyle(for traitCollection: TraitCollection)
      -> ModalPresentationStyle 

After the content managed by the presentation controller is onscreen, this method returns the presentation style to use for the specified set of traits. The default implementation of this method consults its delegate object and returns the value returned by that object’s adaptivePresentationStyle(for:traitCollection:) method. Some system-supplied presentation controllers may also provide a new style that is more suited to the new set of traits.

This method returns the presentation style for the new traits, but does not initiate a transition to the new style. The system initiates the transition to the new style when the traits actually change. When transitioning to new traits, the actual presentation controller object may change. As a result, do not cache the presentation controller object in your code. Always retrieve it from your view controller’s presentationController property.