Find the distance between two geograhical locaions

We need to pass to coordinate to the input to the system and the distance calculated and produced as as output NSNumber

- (NSNumber*)calculateDistanceInMetersBetweenCoord:(CLLocationCoordinate2D)coord1 coord:(CLLocationCoordinate2D)coord2 {

    NSInteger nRadius = 6371; // Earth's radius in Kilometers

    double latDiff = (coord2.latitude - coord1.latitude) * (M_PI/180);

    double lonDiff = (coord2.longitude - coord1.longitude) * (M_PI/180);

    double lat1InRadians = coord1.latitude * (M_PI/180);

    double lat2InRadians = coord2.latitude * (M_PI/180);

    double nA = pow ( sin(latDiff/2), 2 ) + cos(lat1InRadians) * cos(lat2InRadians) * pow ( sin(lonDiff/2), 2 );

    double nC = 2 * atan2( sqrt(nA), sqrt( 1 - nA ));

    double nD = nRadius * nC;

    // convert to meters

    return @(nD*1000);

}


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