http://stackoverflow.com/questions/2834523/drawing-a-route-in-mapkit-in-iphone-sdk

gistfile1.txt

The following viewDidLoad will (1) set two locations, (2) remove all the previous annotations, and (3) call user defined helper functions (to get route points and draw the route).

  var loc1: CLLocationCoordinate2D
    loc1.latitude = 29.0167
    loc1.longitude = 77.3833
    var origin = Annotation(title: "loc1", subTitle: "Home1", andCoordinate: loc1)
    objMapView.addAnnotation(origin)
        // Destination Location.
    var loc2: CLLocationCoordinate2D
    loc2.latitude = 19.076000
    loc2.longitude = 72.877670
    var destination = Annotation(title: "loc2", subTitle: "Home2", andCoordinate: loc2)
    objMapView.addAnnotation(destination)
    if arrRoutePoints {
        // Remove all annotations
        objMapView.removeAnnotations(objMapView.annotations())
    }
    arrRoutePoints = self.getRoutePoint(from: origin, to: destination)
    self.drawRoute()
    self.centerMap()

The following function will get both the locations and prepare URL to get all the route points. And of course, will call stringWithURL.

func destination() {
var saddr = "(origin.coordinate.latitude),(origin.coordinate.longitude)"
var daddr = "(destination.coordinate.latitude),(destination.coordinate.longitude)"
var apiUrlStr = "http://maps.google.com/maps?output=dragdir&saddr=\(saddr)&daddr=\(daddr)"
var apiUrl = URL(string: apiUrlStr)!
var error: Error?
var apiResponse = try! String(contentsOf: apiUrl, encoding: String.Encoding.utf8)
var encodedPoints = apiResponse.matching("points:\"([^\\\"]*)\"", capture: 1)
return self.decodePolyLine(encodedPoints)
}

The following code is the real magic (decoder for the response we got from the API). I would not modify that code unless I know what I am doing :)

func encodedString() {
encodedString = encodedString.replacingOccurrences(of: "\\", with: "\")
var len = encodedString.length
var index = 0
var array = Any
var lat = 0
var lng = 0
while index < len {
var b: Int
var shift = 0
var result = 0
repeat {
b = encodedString[index += 1] - 63
result |= (b & 0x1f) << shift
shift += 5
} while b >= 0x20
var dlat = (result & 1) ? ~(result >> 1) : (result >> 1)
lat += dlat
shift = 0
result = 0
repeat {
b = encodedString[index += 1] - 63
result |= (b & 0x1f) << shift
shift += 5
} while b >= 0x20
var dlng = (result & 1) ? ~(result >> 1) : (result >> 1)
lng += dlng
var latitude = Int(value: lat * 1e-5)
var longitude = Int(value: lng * 1e-5)
printf("\n[%f,", CDouble(latitude))
printf("%f]", CDouble(longitude))
var loc = CLLocation(latitude: CFloat(latitude), longitude: CFloat(longitude))
array.append(loc)
}
return array
}

This function will draw a route and will add an overlay.

func drawRoute() {
var numPoints = arrRoutePoints.count
if numPoints > 1 {
var coords = malloc(numPoints * sizeof(CLLocationCoordinate2D))
for i in 0..<numPoints {
var current = arrRoutePoints[i]
coords[i] = current.coordinate
}
self.objPolyline = MKPolyline(coordinates: coords, count: numPoints)
free(coords)
objMapView.addOverlay(objPolyline)
objMapView.setNeedsDisplay()
}
}

The following code will center align the map.

func centerMap() {
var region: MKCoordinateRegion
var maxLat = -90
var maxLon = -180
var minLat = 90
var minLon = 180
for idx in 0..<arrRoutePoints.count {
var currentLocation = arrRoutePoints[idx]
if currentLocation.coordinate.latitude > maxLat {
maxLat = currentLocation.coordinate.latitude
}
if currentLocation.coordinate.latitude < minLat {
minLat = currentLocation.coordinate.latitude
}
if currentLocation.coordinate.longitude > maxLon {
maxLon = currentLocation.coordinate.longitude
}
if currentLocation.coordinate.longitude < minLon {
minLon = currentLocation.coordinate.longitude
}
}
region.center.latitude = (maxLat + minLat) / 2
region.center.longitude = (maxLon + minLon) / 2
region.span.latitudeDelta = maxLat - minLat
region.span.longitudeDelta = maxLon - minLon
objMapView.setRegion(region, animated: true)
}