Top nav UIScrollView?

[chinjazz]

I've seen a bunch of apps that utilize a horizontal top or bottom scroll nav (the new CNET News app on the top).

Is this a well placed UIScrollView?

I like how the little right and left arrows automatically show up as the user moves the bar hz left or right.

Anyone know how this is done?

[Speed]

After downloading it and looking, I am thinking that the arrows appear after a delegate method such as UIScrollViewWillScroll or something along those lines. Then if it reaches the end it just removes the arrow at the corresponding side. This is at least what I think; may be wrong though.