Instance Method

beginAppearanceTransition(_:animated:)

Tells a child controller its appearance is about to change.

Declaration

func beginAppearanceTransition(_ isAppearing: Bool, animated: Bool)

Parameters

isAppearing

true if the child view controller'€™s view is about to be added to the view hierarchy, false if it is being removed.

animated

If true, the transition is being animated.

Discussion

If you are implementing a custom container controller, use this method to tell the child that its views are about to appear or disappear. Do not invoke viewWillAppear(_:), viewWillDisappear(_:), viewDidAppear(_:), or viewDidDisappear(_:) directly.

See Also

Managing Child View Controllers in a Custom Container

var children: [UIViewController]

An array of view controllers that are children of the current view controller.

func addChild(UIViewController)

Adds the specified view controller as a child of the current view controller.

func removeFromParent()

Removes the view controller from its parent.

var shouldAutomaticallyForwardAppearanceMethods: Bool

Returns a Boolean value indicating whether appearance methods are forwarded to child view controllers.

func endAppearanceTransition()

Tells a child controller its appearance has changed.

func setOverrideTraitCollection(UITraitCollection?, forChild: UIViewController)

Changes the traits assigned to the specified child view controller.

func overrideTraitCollection(forChild: UIViewController) -> UITraitCollection?

Retrieves the trait collection for a child view controller.

class let hierarchyInconsistencyException: NSExceptionName

Raised if the view controller hierarchy is inconsistent with the view hierarchy.