iPhone and Facebook

[spire_bt]

I need to know if this is possible. I want to develop an iPhone app that uses facebook credential to login (this is possible i know) and the create an event (like a dinner) and invite friends from facebook. When the time for the event comes (like 15-20 minutes before the start time) all the users that are attending the event can see how far are the others participants to this event using GPS (Core Location lookups) and see on a map as they move towards the place of the event.
I know this has to be done so that the tracking can be done only when the app is active and for that i plan to set a Local notification to remind the user to turn on the app, but for all the rest i have no idea how can be done. How can the iPhone leave a signature so that my app knows the exact devices that should show on the map

[dany_dev]

i think that the best approach should be to do a your solution server side to manage events, so that you will have a list of events, and people that partecipate on it (with their udid), in this mode you can send also a remote push notification...