Swift implementation to calculate a destination location based on distance and direction from an origin location

destinationBy.swift

import Foundation
import CoreLocation

// Calculate destination location based on origin location, distance (meters) and direction (degrees from north).
// Playing: myOriginLocation.destinationBy(distance: 5.0, direction: 45.0)
// http://www.geomidpoint.com/destination/calculation.html (Spherical earth model)
extension CLLocation {
    func destinationBy(# distance: CLLocationDistance, direction: CLLocationDirection) -> CLLocation {
        let earthRadius     = 6372.7976
        let angularDistance = (distance / 1000) / earthRadius
        let originLatRad    = self.coordinate.latitude * (M_PI / 180)
        let originLngRad    = self.coordinate.longitude * (M_PI / 180)
        let directionRad    = direction * (M_PI / 180)
        
        let destinationLatRad = asin(
            sin(originLatRad) * cos(angularDistance) +
                cos(originLatRad) * sin(angularDistance) *
                cos(directionRad))
        
        let destinationLngRad = originLngRad + atan2(
            sin(directionRad) * sin(angularDistance) * cos(originLatRad),
            cos(angularDistance) - sin(originLatRad) * sin(destinationLatRad))
        
        let destinationLat: CLLocationDegrees = destinationLatRad * (180 / M_PI)
        let destinationLng: CLLocationDegrees = destinationLngRad * (180 / M_PI)
        
        return CLLocation(latitude: destinationLat, longitude: destinationLng)
    }
}