Add and Remove ChildViewController

gistfile1.m

// add child view
    UIViewController* controller = [self.storyboard instantiateViewControllerWithIdentifier:@"test"];
    [self addChildViewController:controller];
    controller.view.frame = CGRectMake(0, 44, 320, 320);
    [self.view addSubview:controller.view];
    [controller didMoveToParentViewController:self];

// remove child view
    UIViewController *vc = [self.childViewControllers lastObject];
    [vc.view removeFromSuperview];
    [vc removeFromParentViewController];

Also make sure to assign nil to child view controller after removing

thanks! you saved my day.
I missed UIViewController *vc = [self.childViewControllers lastObject];

In Swift 3:

Add child view

    let controller = storyboard?.instantiateViewController(withIdentifier: "test") as! UIViewController
    self.addChildViewController(controller)
    controller.view.frame = CGRect(0, 44, 320, 320)
    self.view.addSubview(controller.view)
    controller.didMove(toParentViewController: self)

Remove child view

    let vc = self.childViewControllers.last
    vc.removeFromSuperview()
    vc.removeFromParentViewController()

I work hard on helping more people when I'm helped :)

vc.view.removeFromSuperview()*

I applied the solution but what to do if i want to add a childViewController that's embedded in a navigation controller (the navigation bar won't appear !!).
and thanks in advance.

Thanks a lot. It works like a charm