Why and How Apple Is Collecting Your iPhone Location Data | Gadget Lab | Wired.com: Navalho explained that mobile location services work like this: To get your location, first the iPhone or iPad pulls from Apple’s database containing previously stored information about nearby cell towers and Wi-Fi spots to quickly triangulate your location, and then finally the GPS chip analyzes how long it takes satellite signals to reach the device in order to pinpoint location.
In short, Apple’s stored location database is intended to assist and quicken location processes on iOS mobile devices.