Today I would like to share something that is slightly off topic — how to use iPhone GPS map on the road without a data or WIFI connection. To be more specific, I mean how to use the iPhone Google Map as a GPS (without a network connection on the road) by pre-caching the map. This trick is very useful if you don’t have a data plan or want to avoid the data roaming charges when you are travelling.
Cache the Map First
First you have to cache the area of your destination at various zoom levels with Google Map (you need a data or WIFI connection for this part):
search the location where you will be visiting in Google Map
drag the map around the area to cache it
zoom in & out and drag around again to cache the map at various zoom levels
On the Road
When you are on the road, launch Google Map and press the GPS locator button to locate yourself. The iPhone built-in GPS can communicate with the satellite even when you don’t have a data or WIFI conncection. The purpose of caching the map is to know where you are.
you can not search or find direction
the area or zoom levels that you didn’t cache will not be viewable
sometimes you need to zoom in or out to reset the cached map
This trick was first discovered by my brother accidentally. I have tested it in Toronto, New York City, Los Angeles, Madrid, Barcelona, and Paris. It hasn’t failed on me yet. It has saved me a lot of time and data roaming fees particularly travelling in Europe. You should test it before using it.