iOS App Development For Dummies

Chapter 18

Geocoding

In This Chapter

Understanding geocoding

Getting a feel for reverse geocoding

Displaying the address of the user’s current location

There are two basic ways of identifying where you are on Earth. You can describe your location in coordinates of latitude and longitude, or you can describe your location in terms of an address. The latitude and longitude coordinates are based on geometry (remember Euclid) and on the assumption that the Earth is a regular sphere.

Addresses are based on history and politics. The geographic coordinates of the city now known as St. Petersburg have not changed over time (yes, I know that continental drift has an effect, but to all intents and purposes, it has been in the same place since its founding by Tsar Peter the Great on May 27, 1703). However, St. Petersburg’s name was changed to Petrograd, then to Leningrad, and after that back to St. Petersburg.

Despite the fact that geographic coordinates of a spot on Earth are essentially unchanging and the addresses are subject to change, most people commonly use addresses to describe locations on Earth. Most software that deals with mapping works with geographic coordinates, and it converts ...