Will treating MKCoordinateRegion like a rectangle come back to haunt me?

Background: I'm build a series of location-based apps that make heavy use of maps. These maps are annotated with locations fetched from a server, to which I pass regions of the map I need data for (defined as a lat/long and a latDelta/longDelta, much like MKCoordinateRegion, but with a different location of the reference coordinate). I'm writing a bunch of helper methods/classes to use when managing these regions. Compatibility with iOS 3.x is required (meaning MKMapRect is out).

Question: Am I setting myself up for failure by treating MKCoordinateRegions like rectangles? Specifically, I'm treating their geometry as if it was that of a rectangle, assuming they have basically the same 开发者_如何学Goproperties as rectangles. I've implemented several methods that mirror CGRect's helper methods, such as MKCoordinateRegionUnion/Inset/Outset, etc, and they all pass my unit tests, but I'm starting to question if my underlying assumptions are correct. I know in fact that MKCoordinateRegion does not represent a geometric rectangle, but rather a region of a spherical surface bound by two sets of parallel planes, perpendicular to each other (bonus points if somebody can clue me in on a better term for that).

I'm not experiencing any anomalies yet, but since many apps will be reliant on my understanding of the geometry, I'd rather figure out now if I'm going down the wrong path. The fact that I slept through most of the classes in school dealing with 3d radial geometry doesn't give me much confidence that my intuition is correct.

If you are taking into account the equator, prime meridian and dateline edge cases, I think you will be ok.

Alternatively, you could develop your own MKMapRect like rects. Troy Brant has a great blog post about the how the rects are formed:

http://troybrant.net/blog/2010/01/mkmapview-and-zoom-levels-a-visual-guide/

While the blog post is mainly about zoom levels, all the information there can be used to build up your own map rect library.

As for areas bounded by great circles on the surface of a sphere, they are called spherical polygons. So I guess you could just call them spherical rectangles.