how to add navigation item from view controller embedded in container view

Question

I have a VC (the root VC of a navigation controller) with a container view. The container view embeds another VC. I believe this makes the latter a child VC of the former. I want to add a button to the navigation bar from the code for the child VC. I have tried using parentviewcontoller, but it doesn't work:

UIBarButtonItem *newConvoButton = [[UIBarButtonItem alloc] initWithTitle:@"New convo" style:UIBarButtonItemStyleBordered target:self action:@selector(newConvoInit:)];
self.parentViewController.navigationItem.rightBarButtonItem = newConvoButton;

And I know that code would work fine if it were in the parent VC and I removed the ".parentViewController".

So how can I add a navigation item from an embedded VC?

EDIT:

Here's a screenshot: The TVC on the right logs (null) for self.parentViewController.

Answer 1

rdelmar provides the answer here: interact the navigation controller bar button with embed container view

can't access parent until viewWillAppear