I'm trying to write a category for CLLocation to return the bearing to another CLLocation.
I believe I'm doing something wrong with the formula (calculous is not my strong suit). The returned bearing is always off.
I've been looking at this question and tried applying the changes that were accepted as a correct answer and the webpage it references:
http://stackoverflow.com/questions/3809337/calculating-bearing-between-two-cllocationcoordinate2ds
http://www.movable-type.co.uk/scripts/latlong.html
Thanks for any pointers. I've tried incorporating the feedback from that other question and I'm still just not getting something.
Thanks
Here's my category -
----- CLLocation+Bearing.h
#import <Foundation/Foundation.h>
#import <CoreLocation/CoreLocation.h>
@interface CLLocation (Bearing)
-(double) bearingToLocation:(CLLocation *) destinationLocation;
-(NSString *) compassOrdinalToLocation:(CLLocation *) nwEndPoint;
@end
---------CLLocation+Bearing.m
#import "CLLocation+Bearing.h"
double DegreesToRadians(double degrees) {return degrees * M_PI / 180;};
double RadiansToDegrees(double radians) {return radians * 180/M_PI;};
@implementation CLLocation (Bearing)
-(double) bearingToLocation:(CLLocation *) destinationLocation {
double lat1 = DegreesToRadians(self.coordinate.latitude);
double lon1 = DegreesToRadians(self.coordinate.longitude);
double lat2 = DegreesToRadians(destinationLocation.coordinate.latitude);
double lon2 = DegreesToRadians(destinationLocation.coordinate.longitude);
double dLon = lon2 - lon1;
double y = sin(dLon) * cos(lat2);
double x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon);
double radiansBearing = atan2(y, x);
return RadiansToDegrees(radiansBearing);
}