Adds the specified view controller as a child of the current view controller.
- iOS 5.0+
- tvOS 9.0+
The view controller to be added as a child.
This method creates a parent-child relationship between the current view controller and the object in the
child parameter. This relationship is necessary when embedding the child view controller’s view into the current view controller’s content. If the new child view controller is already the child of a container view controller, it is removed from that container before being added.
This method is only intended to be called by an implementation of a custom container view controller. If you override this method, you must call
super in your implementation.