A recent Google search reveals that there isn't much discussion about the recently introduced region monitoring feature on the iPhone. A couple of us were looking into how it could be used, and I created a toy project which creates and monitors regions. The project itself is really simple, it just tracks the iPhones current location using the significant location change APIs, and allows you to create a region of constant radius. It then monitors this region, and notifies one when one enter or exits this region.

At some point, once I am done actually getting things to work correctly, I'll post more information, my current intention was to merely provide a starting point. So far my observations with the current code are

• Region boundary crossings seem to be pretty fuzzy. In some case I get notified very close to where I would have expected, while in other cases it can be some distance from my expected boundary.
• For some reason when crossing a particular location causes the iPhone to generate a exiting region event, walking back through that region won't necessarily generate an entering region event.

These defects could be because of how the code is written (if you happen to notice something wrong, please leave a comment), as stated above I'll post more when I figure more of this out.