I want to create an app that gives a signal when i am some 100 feet within a certain GPS coordinate.
I have looked around a bit to no avail yet here.
Can this be done with corona?
If not, then maybe with the bump-technique?

thanks!
p.s. if this app would need coding on serverside, thats no problem

All you have to do is get the GPS coordinates at some interval and do some simple math to find out how far you are from the desired (target) coordinates.

The most accurate way to compute this distance is the great circle method.
http://en.wikipedia.org/wiki/Great-circle_distance

If you don't care about accuracy so much simple right angle geometry can be used also.

thanks haucks, thats a good start yes!
good to hear it can be done :0-

Can I ask what your application is?

Well, its in the design stage, but its a framework that alerts people with discounts etc when they are nearby or enter a specific storec.q. Business.
First i need to know how to have the iphone keep looking at the coordinates all the time in the background. Any toughts on this?
Thanks