Moving a CLLocation by x meters

Question

I have a CLLocation defined, and I\'d like to move that point x meters to the east and y meters to the south. How may I achieve that?

Answer 1

Swift 4.2 as a CGPoint extension

Derived from Peter O.'s solution

FloatingPoint extension: thanks to https://stackoverflow.com/a/29179878/2500428

extension FloatingPoint
{
    var degreesToRadians: Self { return self * .pi / 180 }
    var radiansToDegrees: Self { return self * 180 / .pi }
}

extension CGPoint
{
    // NOTE: bearing is in radians
    func locationWithBearing(bearing: Double, distanceMeters: Double) -> CGPoint
    {
        let distRadians = distanceMeters / (6372797.6) // earth radius in meters

        let origLat = Double(self.y.degreesToRadians)
        let origLon = Double(self.x.degreesToRadians)

        let newLat = asin(sin(origLat) * cos(distRadians) + cos(origLat) * sin(distRadians) * cos(bearing))
        let newLon = origLon + atan2(sin(bearing) * sin(distRadians) * cos(origLat), cos(distRadians) - sin(origLat) * sin(newLat))

        return CGPoint(x: newLon.radiansToDegrees, y: newLat.radiansToDegrees)
    }
}

Usage:

let loc = CGPoint(x: lon, y: lat)
let newLoc = loc.locationWithBearing(bearing: 90.degreesToRadians, distanceMeters: 500.0)