Techniques for offline reverse geocoding on a mobile device?

Question

I am working on a mobile mapping application (currently iOS, eventually Android) - and I am struggling with how to best support reverse geocoding from lat/long to Country/St

Answer 1

If you're looking for an approach based on a quadtree, try Yggdrasil. It generates a quadtree based on country polygon data. A Ruby example script can be found here.