Toolbar in UITableViewController

I've got a UITableViewController that's a child of a UINavigationController, and in the UITableViewController's viewDidLoad I've tried to add toolbar items like so:

self.navigationController.toolbarHidden = NO;
UIBarButtonItem *delete = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemTrash target:self action:@selector(trashButtonPressed)];
UIBarButtonItem *forward = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(actionButtonPressed)];
[self.navigationController setToolbarItems:@[delete, forward]];

Unfortunately I see the toolbar, but there are no buttons. What have I done wrong?

I also tried directly setting the items on self.navigationController.toolbar but that didn't work either. I'd really rather do this directly from the storyboard, but I'm not seeing a good way to do that either.