What is the fastest way to sort a lot of locations on distance?

I want to sort lots of locations (waypoints) on their distance from the current location. The current location is, of course, a moving target, so for every location update, recomputing the distance for every location is necessary. But only recomputing for close-by locations would by enough.

I currently use core-data, and store the distance to the current location as an attribute in the table (but only update is when it is changed) from within the configurecell: atindexpath: method. That sort of works, but the application is not responding while core-data automagically is updating all distances. This works for 250 locations, but for 5000 it crashes. Мне нужно, чтобы он работал для 10.000 местоположений, хотя мне, вероятно, нужно только 1000 ближайших местоположений или около того.

Идеи, которые я еще не пробовал: Store all distances in a separate in-memory array with nothing but record id and distance. Then sort the array on distance. Problem is that then I can not use a FetchedResultsController because there is no sort field in the database.

Filter locations based on their latitude and longitude by using a predicate. Then only present the filtered locations.

Do the recalculation of distances in a separate thread.

None of the ideas seems easy enough to just try it out.

Anybody with suggestions, different ideas, a variation on my ideas?