Swift - Distance between two lat and longs.

distanceLat&Long.swift

struct MapPoint {
    var lat : Double = 0
    var long : Double = 0
}

class DistanceCalculator {
    var fromMP : MapPoint
    var toMP : MapPoint
    
    var fLat : Double!
    var fLong : Double!
    var tLat : Double!
    var tLong : Double!
    
    init(from: MapPoint, to: MapPoint){
        fromMP = from
        toMP = to
        fLat = dToR(fromMP.lat)
        fLong = dToR(fromMP.long)
        tLat = dToR(toMP.lat)
        tLong = dToR(toMP.long)
    }
    
    //Degrees to Radians
    func dToR(val: Double) -> Double {
        return val * M_PI / 180
    }
    
    func inMiles() -> Double {
        var dlon = fLong - tLong
        var dlat = fLat - tLat
        let a = pow(sin(dlat/2), 2) + (cos(fLat) * cos(tLat)) * pow(sin(dlon/2), 2)
        let c = 2 * atan2(sqrt(a), sqrt(1-a))
        let d = 3961 * c
        return d
    }
    
    func toString() -> String {
        return "The two points are \(self.inMiles()) miles apart"
    }
}

var mp1 = MapPoint(lat: 38.898556, long: -77.037852)
var mp2 = MapPoint(lat: 38.897147, long: -77.043934)

var dc = DistanceCalculator(from: mp1, to: mp2)
var distance = dc.inMiles()
println(dc.toString())