alert me when i get close

I would like to develop an application whereby; 1. A system administrator can define one or more geographical areas on a map using an ipad/mac/pc. 2. The system administrator can also define information specific to the geographical area defined. 3. Via iphone/android app, a user receives the information defined at 2 when entering the geographical area defined at 1 I am looking for an engine only, not a UI. I would expect that the following is relevant for Apple; Handling Boundary-Crossing Events for a Geographical Region By default, every time the user’s current location crosses a boundary region, the system generates an appropriate region event for your app. Apps can implement the following methods to handle boundary crossings: locationManager:didEnterRegion: locationManager:didExitRegion: You can customize which boundary-crossing events notify your app by explicitly setting the notifyOnEntry and notifyOnExit properties of the CLRegion class when you define and register a region. (The default value of both properties is YES.) For instance, if you want to be notified only when the user exits the boundary of a region, you can set the value of the region’s notifyOnEntry property to NO. The system does not report boundary crossings until the boundary plus a system-defined cushion distance is exceeded. This cushion value prevents the system from generating numerous entered and exited events in quick succession while the user is traveling close the edge of the boundary. When a region boundary is crossed, the most likely response is to alert the user of the proximity to the target item. If your app is running in the background, you can use local notifications to alert the user; otherwise, you can simply post an alert.