You wrote that you have UIViewController there and not UITableViewController - if you have UIViewController you have to have a property there. I assume that here everything is ok.. But check.
What I am doing while working with containers views is adding element by:
_someVC = [self.storyboard instantiateViewControllerWithIdentifier:@"SomeVC"];
[self addChildViewController:_someVC];
_someVC.view.frame = _containerView.bounds;
[_containerView addSubview:_someVC.view];
[_someVC didMoveToParentViewController:self];
And not with IB. Hope that helps.