draw route

import UIKit
import MapKit

class ViewController: UIViewController, MKMapViewDelegate {
    
    @IBOutlet weak var mapView: MKMapView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 1.
        mapView.delegate = self
        
        // 2.苹果在中国区域默认使用高德地图，这里使用北京的两个地点
        let sourceLocation = CLLocationCoordinate2D(latitude: 39.906421, longitude: 116.397633)
        let destinationLocation = CLLocationCoordinate2D(latitude: 39.935865, longitude: 116.455381)
        
        // 3.
        let sourcePlacemark = MKPlacemark(coordinate: sourceLocation, addressDictionary: nil)
        let destinationPlacemark = MKPlacemark(coordinate: destinationLocation, addressDictionary: nil)
        
        // 4.
        let sourceMapItem = MKMapItem(placemark: sourcePlacemark)
        let destinationMapItem = MKMapItem(placemark: destinationPlacemark)
        
        // 5.
        let sourceAnnotation = MKPointAnnotation()
        sourceAnnotation.title = "Tian'anmen Square"
        
        if let location = sourcePlacemark.location {
            sourceAnnotation.coordinate = location.coordinate
        }
        
        
        let destinationAnnotation = MKPointAnnotation()
        destinationAnnotation.title = "Taikoo Li Sanlitun"
        
        if let location = destinationPlacemark.location {
            destinationAnnotation.coordinate = location.coordinate
        }
        
        // 6.
        self.mapView.showAnnotations([sourceAnnotation,destinationAnnotation], animated: true )
        
        // 7.
        let directionRequest = MKDirectionsRequest()
        directionRequest.source = sourceMapItem
        directionRequest.destination = destinationMapItem
        directionRequest.transportType = .automobile
        
        // Calculate the direction
        let directions = MKDirections(request: directionRequest)
        
        // 8.
        directions.calculate { (response, error) in
            guard let response = response else {
                if let error = error {
                    print("Error: \(error)")
                }
                return
            }
            let route = response.routes[0]
            self.mapView.add(route.polyline, level: MKOverlayLevel.aboveRoads)
            
            let rect = route.polyline.boundingMapRect
            self.mapView.setRegion(MKCoordinateRegionForMapRect(rect), animated: true)
        }
    }
    
    func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
        let renderer = MKPolylineRenderer(overlay: overlay)
        renderer.strokeColor = UIColor.red
        renderer.lineWidth = 3.0
        return renderer
    }
    
}

effect

draw map.png