Ответ 1
Вы должны использовать Core Location Framework. Поэтому не забудьте добавить и импортировать Core Location Framework.
#import <CoreLocation/CoreLocation.h>
CLLocation *locA = [[CLLocation alloc] initWithLatitude:lat1 longitude:long1];
CLLocation *locB = [[CLLocation alloc] initWithLatitude:lat2 longitude:long2];
CLLocationDistance distance = [locA distanceFromLocation:locB];
//distance in Meters
//1 meter == 100 centimeter
//1 meter == 3.280 feet
//1 square meter == 10.76 square feet
[locA release];
[locB release];