title: iphone navigation UI 2 levels
body: <p>the first screen shows a list of categories in tableview
  select one item goes to the next screen which shows a list of items in that category in a tableview and shows a home nav button back.
  and selecting an item in this view would take me to a detail view showing a nav button back to that category i just selected.</p>
  
  <p>all the examples i've found are 1 level only.</p>
  
  <p>does anyone know of any examples or this how to program this?</p>