Global Variable


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


const NSExceptionName UIViewControllerHierarchyInconsistencyException;


When a view controller'€™s view is added to the view hierarchy, the system walks up the view hierarchy to find the first parent view that has a view controller. That view controller must be the parent of the view controller whose view is being added. Otherwise, this exception is raised. This consistency check is also performed when a view controller is added as a child by calling the addChildViewController: method.

It is also allowed for a view controller that has no parent to add its view to the view hierarchy. This is generally not recommended, but is useful in some special cases.

See Also

Managing Child View Controllers in a Custom Container


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

- addChildViewController:

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

- removeFromParentViewController

Removes the view controller from its parent.

- transitionFromViewController:toViewController:duration:options:animations:completion:

Transitions between two of the view controller'€™s child view controllers.


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

- beginAppearanceTransition:animated:

Tells a child controller its appearance is about to change.

- endAppearanceTransition

Tells a child controller its appearance has changed.

- setOverrideTraitCollection:forChildViewController:

Changes the traits assigned to the specified child view controller.

- overrideTraitCollectionForChildViewController:

Retrieves the trait collection for a child view controller.