Example of my use of UIViewController containment lifecycle methods inside a custom tab bar controller.

gistfile1.m

- (void) setSelectedViewController:(UIViewController<SFCustomTabbedViewController> *)selectedViewController {
    if (_selectedViewController != selectedViewController) {
        if (_selectedViewController) {
            NSUInteger selectedViewControllerIndex = [self.viewControllers indexOfObject:_selectedViewController];
            if (selectedViewControllerIndex != NSNotFound) {
                UIButton *tabButton = [self.tabButtons objectAtIndex:selectedViewControllerIndex];
                tabButton.selected = NO;
            }
            
            [_selectedViewController willMoveToParentViewController:nil];
            [_selectedViewController.view removeFromSuperview];
            [_selectedViewController removeFromParentViewController];
        }
        
        _selectedViewController = selectedViewController;
        
        if (_selectedViewController) {
            [self view]; // guarantee loadView gets called
            [self addChildViewController:_selectedViewController];
            
            _selectedViewController.view.autoresizingMask =
            UIViewAutoresizingFlexibleWidth |
            UIViewAutoresizingFlexibleHeight;
            _selectedViewController.view.frame = self.selectedViewControllerContainerView.bounds;
            [self.selectedViewControllerContainerView addSubview:_selectedViewController.view];
            
            [_selectedViewController didMoveToParentViewController:self];
            
            NSUInteger selectedViewControllerIndex = [self.viewControllers indexOfObject:_selectedViewController];
            if (selectedViewControllerIndex != NSNotFound) {
                UIButton *tabButton = [self.tabButtons objectAtIndex:selectedViewControllerIndex];
                tabButton.selected = YES;
            }
        }
    }
}