Best practice for using lat/long within a UIView (not MKMapView)

Question

Basically i have a list of POI's (name,lat,long) and i want to draw them on the UIView, relative to my current lat/long. I'm looking for some best practice for mapping these POI (lat/long) to a UIView.

I don't want to use MKMapView (no need for displaying map-data).

I was reading:

http://developer.apple.com/library/ios/#documentation/general/conceptual/Devpedia-CocoaApp/CoordinateSystem.html

But I'm clueless how i get from a CLLocation to a (x,y) on my UIView. I only want to draw those POI's around my current location. So, for example if my screen would represent a 20 by 30 KM region, how do i map my POI's to their corresponding (x,y) coordinates?

Thanks.

Answer 1

What you're doing is a little strange, but you can convert latitude/longitude to a CGPoint-like struct called an MKMapPoint. An MKMapPoint has an x and y value which correspond to points on a map. Imagine if you laid out a flat map of the world, and 0,0 was the top left. MKMapPoint is a point on that map using that coordinate system.

Use the function MKMapPointForCoordinate() to convert a CLLocationCoordinate2D to an MKMapPoint

MKMapPoint myMapPoint = MKMapPointForCoordinate(myLocationCoordinate);

When you get the list of points, you'll have to do something like finding the max and min x and y values, then fitting all the points into your view using those values, otherwise you'll end up with a load of very close points in one place in your view.