I found the answer to removing the gap with the nav bars created the way I did it though:
http://justingallagher.com/post/75183205/quick-tip-remove-gap-between-iphone-status-bar-and. He suggests to do this:
[viewController.view setFrame: [viewController.view bounds]];

I did this to the tab bar controller and it removed the gap.

As with your example, I initially had navigation bars that I put in the screens with Interface Builder with static headings, as you described, but was unable to interact with them so removed them and added them programmatically. As described in several sources including Apple’s, the Navigation controller is constructed using initWithRootViewController:, passing in the view controller for the initial screen. I then modified my app delegate to add the views of the navigation controller as subviews of the tab controller viewController views (instead of the original UIView screens.) The problem I am having with that, however, is that there is a white row between the status bar and the navigation bar on all the pages, which looks equivalent to the height of the status bar. Do you know how I can correct this, or alternately (and preferably, probably), how do you interact with the Navigation Bars added to the screens as you did, with Interface Builder?

Thanks again for your great articles!