Calculating bearing between two CLLocation points in Swift [duplicate]

Question

I'm trying to calculate a bearing between two CLLocation points in swift-only code. I've run into some difficulty and was assuming this is a pretty simple function. Stack overflow didn't seem to have anything listed.

func d2r(degrees : Double) -> Double {     return degrees * M_PI / 180.0 }  func RadiansToDegrees(radians : Double) -> Double {     return radians * 180.0 / M_PI }   func getBearing(fromLoc : CLLocation, toLoc : CLLocation) {      let fLat = d2r(fromLoc.coordinate.latitude)     let fLng = d2r(fromLoc.coordinate.longitude)     let tLat = d2r(toLoc.coordinate.latitude)     let tLng = d2r(toLoc.coordinate.longitude)      var a = CGFloat(sin(fLng-tLng)*cos(tLat));     var b = CGFloat(cos(fLat)*sin(tLat)-sin(fLat)*cos(tLat)*cos(fLng-tLng))      return atan2(a,b) } 

I'm getting an error with my atan2 call about lvalue cgfloat or something...

Answer 1

Here is an Objective-C solution

• CLLocation Category for Calculating Bearing w/ Haversine function

which can easily be translated to Swift:

func degreesToRadians(degrees: Double) -> Double { return degrees * .pi / 180.0 } func radiansToDegrees(radians: Double) -> Double { return radians * 180.0 / .pi }  func getBearingBetweenTwoPoints1(point1 : CLLocation, point2 : CLLocation) -> Double {      let lat1 = degreesToRadians(degrees: point1.coordinate.latitude)     let lon1 = degreesToRadians(degrees: point1.coordinate.longitude)      let lat2 = degreesToRadians(degrees: point2.coordinate.latitude)     let lon2 = degreesToRadians(degrees: point2.coordinate.longitude)      let dLon = lon2 - lon1      let y = sin(dLon) * cos(lat2)     let x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon)     let radiansBearing = atan2(y, x)      return radiansToDegrees(radians: radiansBearing) } 

The result type is Double because that is how all location coordinates are stored (CLLocationDegrees is a type alias for Double).