As iOS 8 is out, there is a feature that show \"Suggested App\" on lockscreen based on your location.
The question is if I have an app, how can I define the location
The "suggested app" feature works also with iBeacons. When you make your application listen to a CLBeaconRegion with a certain iBeacon UUID, that application will be visible in the lock screen when you're close enough to that type of an iBeacon.
CLBeaconRegion