Best way to monitor for a large (50000+) number of regions

I want to create an app which does a specific action when the user enters a certain area.

Since the regions I want to monitor reside server-side (approx. 50.000 locations) and the number of regions is far too large to be registered for monitoring all at once, I want to start monitoring for regions which are close to the curr开发者_运维问答ent location of the user.

To accomplish this I am thinking about using startMonitoringSignificantLocationChanges to monitor whether the user has changed location and then use locationManager:didUpdateToLocation:fromLocation: to register new regions to monitor and unregister regions which are now too far away.

My questions:

• Am I allowed do a call to a web-service in didUpdateToLocation while the app is in the background?
• Is this the best way to implement this kind of functionality or do you know of a better way?

Thanks.

What you want is a space-filling-curve for example a z-curve of a hilbert-curve. It reduce the 2D problem to a 1D problem but it's most likely not answering your question.