I implemented what I believed to be the correct code for the Challenge to Chapter 4 (displaying) the heading information.
I added two labels to the UI so that I could walk about outside to see if it changed.
Unfortunately the heading information did not display so I looked at this topic under the first edition:
My device is an iPhone 3G, on which the heading information does not work.
At least by looking at this topic I found out I implemented the correct code