Adding and removing a view controller on top of another - on iOS - without using modal presentation

ChilViewController.m

// GOAL
// viewControllerA
// |_ viewControllerB 

UIViewController *viewControllerA = ...;
UIViewController *viewControllerB = ...;

// Adding 
[viewControllerA addChildViewController:viewControllerB];
[viewControllerA.view addSubview:viewControllerB.view];

// Removing
[viewControllerB willMoveToParentViewController:nil];
[viewControllerB.view removeFromSuperview];
[viewControllerB removeFromParentViewController];