How can I show polylines of two or more different pins for one destination?

Question

I'm trying to show one location destination for two or more different pins locations, but problem is that when i change the location of pin the routes doesn't reset. For example, when i started app and set a location, it shows a route, but when i add or change location on map the previous route doesn't disapper.

First View of Directions http://i.hizliresim.com/kGOvy9.png

Second View of Directions http://i.hizliresim.com/pX6Ppn.png

// Adding or changing the location of destination pin

@IBAction func longpress(_ sender: UILongPressGestureRecognizer) {

    let location =  sender.location(in: self.map)
    let locCoordinate = self.map.convert(location, toCoordinateFrom: self.map)

    annotation.coordinate = locCoordinate
    annotation.title = "Store"
    annotation.subtitle = "Location of Store"

    self.map.addAnnotation(annotation)

    annotationLat = annotation.coordinate.latitude
    annotationLong = annotation.coordinate.longitude

    for item in arr {
        let dic = item as? [String: Any]
        pinDestinations(lat: dic?["lat"] as! CLLocationDegrees, long: dic?["long"] as! CLLocationDegrees)
    }

    let directions = MKDirections(request: request)

    directions.calculate { [unowned self] response, error in
        guard let unwrappedResponse = response else { return }

        for route in unwrappedResponse.routes {
            // I tried here remove previous polyline while i'm adding new one 
            self.map.removeOverlays([route.polyline])
        }
    }


func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
    let renderer = MKPolylineRenderer(polyline: overlay as! MKPolyline)

    renderer.strokeColor = UIColor.blue
    renderer.lineWidth = 1
    return renderer
}  }

Answer 1

You can define property to keep track of previously added polylines:

var polylines: [MKPolyline]?

Then, when you update directions, remove the old polylines (if any) from the map, update the polylines with the new values, and then add them to the map:

func updateDirections() {
    let request = ...

    let directions = MKDirections(request: request)
    directions.calculate { response, error in
        guard let response = response, error == nil else {
            print("\(error)")
            return
        }

        if let polylines = self.polylines {
            self.mapView.removeOverlays(polylines)
        }

        self.polylines = response.routes.map { $0.polyline }
        self.mapView.addOverlays(self.polylines!)
    }
}