iPhone app for gps tracking

We require an iPhone/iPad app to run in the background and submit a string of location data to an external server. The app MUST run in the background and submit data periodically. Some basic settings should be set from the "General" section of the iphone menu. Settings should include; 1. IP address of the server to send the data to 2. The port number to use 3. The interval time to send the string. The app should be started, then should run in the background, sending the string to the specificed server over the specified port number at specified intervals. The code should be well documented (commented)