Render multipolylines onto one map in swift

I have want to try and put a few different walking zones onto a map using polylines. The app works perfectly for one, however when i try and add walking zone 2 the polyine is not shown between zone points 2 at all. how can I get this to show the polyline for zone 1 and zone 2?

I can't seem to figure out where I am going wrong with this as it works perfectly for walking zone one but not when i add in the extra zone.

import UIKit
import MapKit

class customPin: NSObject, MKAnnotation {
var coordinate: CLLocationCoordinate2D
var title: String?
var subtitle: String?

init(pinTitle:String, pinSubTitle:String, location:CLLocationCoordinate2D) {
    self.title = pinTitle
    self.subtitle = pinSubTitle
    self.coordinate = location
}
}

class ViewController: UIViewController, MKMapViewDelegate {

@IBOutlet weak var mapView: MKMapView!
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    //co-ordinates
    let zone1S = CLLocationCoordinate2D(latitude: 52.100525, longitude: -9.623071)
    let zone1E = CLLocationCoordinate2D(latitude: 52.07241, longitude: -9.575299)

    let zone2S = CLLocationCoordinate2D(latitude: 52.054161, longitude: -9.385031)
    let zone2E = CLLocationCoordinate2D(latitude: 52.081185, longitude: -9.247033)


    //pins
    let zone1PinS = customPin(pinTitle: "Zone 1 Start", pinSubTitle: "", location: zone1S)
    let zone1PinE = customPin(pinTitle: "Zone 1 End", pinSubTitle: "", location: zone1E)
    self.mapView.addAnnotation(zone1PinS)
    self.mapView.addAnnotation(zone1PinE)

    let zone2PinS = customPin(pinTitle: "Zone 2 Start", pinSubTitle: "", location: zone2S)
    let zone2PinE = customPin(pinTitle: "Zone 2 End", pinSubTitle: "", location: zone2E)
    self.mapView.addAnnotation(zone2PinS)
    self.mapView.addAnnotation(zone2PinE)


    let zone1PlacemarkS = MKPlacemark(coordinate: zone1S)
    let zone1PlacemarkE = MKPlacemark(coordinate: zone1E)

    let zone2PlacemarkS = MKPlacemark(coordinate: zone2S)
    let zone2PlacemarkE = MKPlacemark(coordinate: zone2E)


    let directionRequest = MKDirections.Request()
    directionRequest.source = MKMapItem(placemark: zone1PlacemarkS)
    directionRequest.destination = MKMapItem(placemark: zone1PlacemarkE)

    //type of commute
    directionRequest.transportType = .automobile



    let directions = MKDirections(request: directionRequest)
    directions.calculate { (response, error) in
        guard let directionResonse = response else {
            if let error = error {
                print("we have error getting directions==\(error.localizedDescription)")
            }
            return
        }

        let route = directionResonse.routes[0]
        self.mapView.addOverlay(route.polyline, level: .aboveRoads)


        let rect = route.polyline.boundingMapRect
        //zooming in on location
       // self.mapView.setRegion(MKCoordinateRegion(rect), animated: true)
    }

    //set delegate for mapview
    self.mapView.delegate = self
}


func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    let renderer = MKPolylineRenderer(overlay: overlay)
    renderer.strokeColor = UIColor.red
    renderer.lineWidth = 5.0
    return renderer
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}


}

when i try and add walking zone 2

But you don't add it. You are saying

let directionRequest = MKDirections.Request()
directionRequest.source = MKMapItem(placemark: zone1PlacemarkS)
directionRequest.destination = MKMapItem(placemark: zone1PlacemarkE)

You have only one direction request, and it uses the zone1PlacemarkS and zone1PlacemarkE, so those are the directions you get. You never make a direction request for the two zone2 placemarks; you just throw them away, unused. (Indeed, I would expect the compiler to warn you about that.)