How to link to Google Map directions from iPhone app

Question

I have been developing a location based application and would ideally like to link directly to the directions using the Google application.

I have seen a few applications such as AroundMe which already seem to do this but I can't work out how they have managed to implement it

Answer 1

The question was about opening maps with the navigation directions displayed, not just the map. The iPhone's URL scheme supports a source & destination address - try, for example:

NSString* urlString = @"http://maps.google.com/maps?saddr=London+UK&daddr=Birmingham+UK";
[[UIApplication sharedApplication] openURL:[NSURL URLWithString: urlString]];