Objective C / iPhone comparing 2 CLLocations /GPS coordinates help

Question

Ok , so thanks to Claus Broch I made some progress with comparing two GPS locations. I need to be able to say "IF currentlocation IS EQUAL TO (any GPS position from a list ) THEN do something

My code at the moment is :

CLLocationCoordinate2D bonusOne; bonusOne.latitude = 37.331689; bonusOne.longitude = -122.030731;

Which is the simulators GPS location at Infinite Loop

CLLocation *loc1 = [[CLLocation alloc] initWithLatitude:bonusOne.latitude longitude:bonusOne.longitude];
double distance = [loc1 getDistanceFrom:newLocation];
if(distance <= 10000000) {

Then do something }

Any number under 10000000 and it assumes that there is no match. Any ideas ? Thanks is advance.

Answer 1

Yes, you can use getDistanceFrom to get the distance between two points. The distance is in meters. You can use that comparison, compared with the current horizontal accuracy from the location manager, to determine if you are roughly at the "bonus one" position.

CLLocation *bonusLocation = [[CLLocation alloc] initWithLatitude:bonusOne.latitude longitude:bonusOne.longitude];
float distance = [bonusLocation getDistanceFrom:newLocation];
float threshold = 2 * [newLocation horizontalAccuracy]; // Or whatever you like
if(distance <= threshold) {
  // You are at the bonus location.
}