In the interface builder make sure that you've set the navigation bar and tab bar spacers up. It should be the first list of options on the first tab in the Interface builder Properties view. This will make your view mimic the amount of space it has when loaded in the view.
From there you can also choose the option to clip the subview. The interface builder also allows you to set resize options for the view. If the subview your adding wasn't created in the interface builder you'll have to specify those options manually.
Lastly make sure that your appending the subview to the correct view, and not the tab bar controller or navigation controller.
Best bet is to make sure the subview your addings dimensions are appropriate for the amount of space you have by creating a frame using CGRect.
