Display route on map in Swift

Question

I am trying to draw the route between two points on Apple map (Swift code). The following structure is used to store the coordinates

struct GeoLocation {
    var latitude: Double
    var longitude: Double

    func distanceBetween(other: GeoLocation) -> Double {
        let locationA = CLLocation(latitude: self.latitude, longitude: self.longitude)
        let locationB = CLLocation(latitude: other.latitude, longitude: other.longitude)
        return locationA.distanceFromLocation(locationB)
    }
}

self.foundLocations - is an array of these structures

In the custom class I recieve the coordinates of the points on the map.

var coordinates = self.foundLocations.map{$0.coordinate}

Then I draw the route on the map

self.polyline = MKPolyline(coordinates: &coordinates, count: coordinates.count)
        self.mapView.addOverlay(self.polyline, level: MKOverlayLevel.AboveRoads)

To draw the route I use the following method from MKMapViewDelegate

func mapView(mapView: MKMapView!, rendererForOverlay overlay: MKOverlay!) -> MKOverlayRenderer! {
    if let polylineOverlay = overlay as? MKPolyline {
        let render = MKPolylineRenderer(polyline: polylineOverlay)
        render.strokeColor = UIColor.blueColor()
        return render
    }
    return nil
}

Instead of the actual route laying on roads I get just a straight line between two points. How can I display the actual route?

Answer 1

You actually have to fetch the route from Apple's maps' server using calculateDirectionsWithCompletionHandler.

First create the relevant MKMapItems for both the source and destination, ex:

let geocoder = CLGeocoder()
let location = CLLocation(latitude: sourceLatitude, longitude: sourceLongitude)

geocoder.reverseGeocodeLocation(location, completionHandler: {
        (placemarks:[AnyObject]?, error:NSError?) -> Void in
        if placemarks?.count > 0 {
            if let placemark: MKPlacemark = placemarks![0] as? MKPlacemark {
                self.source =  MKMapItem(placemark: placemark)
            }
        }
        })

(Repeat for destination.)

Then fetch the MKRoute, ex:

let request:MKDirectionsRequest = MKDirectionsRequest()

// source and destination are the relevant MKMapItems
request.setSource(source)
request.setDestination(destination)

// Specify the transportation type
request.transportType = MKDirectionsTransportType.Automobile;

// If you're open to getting more than one route, 
// requestsAlternateRoutes = true; else requestsAlternateRoutes = false;
request.requestsAlternateRoutes = true

let directions = MKDirections(request: request)

directions.calculateDirectionsWithCompletionHandler ({
    (response: MKDirectionsResponse?, error: NSError?) in

    if error == nil {
        self.directionsResponse = response
        // Get whichever currentRoute you'd like, ex. 0
        self.route = directionsResponse.routes[currentRoute] as MKRoute
    }
})

Then after retrieving the MKRoute, you can add the polyline to the map like so:

mapView.addOverlay(route.polyline, level: MKOverlayLevel.AboveRoads)

Answer 2

Swift 3 and reusable conversion of Lyndsey Scott's answer:

final class Route {

    static func getRouteFor(
        source: CLLocationCoordinate2D,
        destination: CLLocationCoordinate2D,
        completion: @escaping (

        _ route: MKRoute?,
        _ error: String?)->()

        ) {

        let sourceLocation = CLLocation(

            latitude: source.latitude,
            longitude: source.longitude

        )

        let destinationLocation = CLLocation(

            latitude: destination.latitude,
            longitude: destination.longitude

        )

        let request = MKDirectionsRequest()

        self.getMapItemFor(location: sourceLocation) { sourceItem, error in

            if let e = error {

                completion(nil, e)

            }

            if let s = sourceItem {

                self.getMapItemFor(location: destinationLocation) { destinationItem, error in

                    if let e = error {

                        completion(nil, e)

                    }

                    if let d = destinationItem {

                        request.source = s

                        request.destination = d

                        request.transportType = .walking

                        let directions = MKDirections(request: request)

                        directions.calculate(completionHandler: { response, error in

                            if let r = response {

                                let route = r.routes[0]

                                completion(route, nil)

                            }

                        })

                    }

                }

            }

        }

    }

    static func getMapItemFor(
        location: CLLocation,
        completion: @escaping (

        _ placemark: MKMapItem?,
        _ error: String?)->()

        ) {

        let geocoder = CLGeocoder()

        geocoder.reverseGeocodeLocation(location) { placemark, error in

            if let e = error {

                completion(nil, e.localizedDescription)

            }

            if let p = placemark {

                if p.count < 1 {

                    completion(nil, "placemark count = 0")

                } else {

                    if let mark = p[0] as? MKPlacemark {

                        completion(MKMapItem(placemark: mark), nil)

                    }

                }

            }

        }

    }

}

Usage:

Route.getRouteFor(source: CLLocationCoordinate2D, destination: CLLocationCoordinate2D) { (MKRoute?, String?) in
       <#code#>
}