如何获取从用户位置到另一个特定位置的路线？

Question

我在地图上有2个位置。第一个是带有蓝点地标的用户当前位置。第二个是用红点地标指定的用户当前位置附近的餐厅位置。我想获取从用户当前位置到餐厅位置的路线。定义latitude: 38.00001 and longitude: 27.08980之类的纬度和经度值时，我正在获取路线。

我也正在从api到每个红点地标获取每个餐厅的位置。但不要获取从用户当前位置到餐厅位置的路线。

我正在使用以下代码获取餐厅位置：

var viewModel: DetailsViewModel? {
    didSet {
        updateView()
    }
    willSet {
        updateView()
    }
}

func updateView() {
    if let viewModel = viewModel {
      detailsFoodView?.priceLabel?.text = viewModel.price
      detailsFoodView?.hoursLabel?.text = viewModel.isOpen
      detailsFoodView?.locationLabel?.text = viewModel.phoneNumber
      detailsFoodView?.ratingsLabel?.text = viewModel.rating
      detailsFoodView?.collectionView?.reloadData()
      centerMap(for: viewModel.coordinate)
      print("detail restaurant destination : \(viewModel.coordinate)")
      title = viewModel.name
      print("title: \(title)")
    }
}

func centerMap(for coordinate: CLLocationCoordinate2D) {
    let region = MKCoordinateRegion(center: coordinate, latitudinalMeters: 100, longitudinalMeters: 100)
    let annotation = MKPointAnnotation()
    annotation.coordinate = coordinate
    detailsFoodView?.mapView?.addAnnotation(annotation)
    detailsFoodView?.mapView?.setRegion(region, animated: true)
}
}

，然后在viewDidLoad()中获得如下指示：

let sourceCoordinates = locationManager.location?.coordinate

问题在这里

我没有让每个餐馆的经度和纬度值设为destCoordinates。通常，我会接受viewModel.coordinate。

但是如果我使用

let destCoordinates = CLLocationCoordinate2D(latitude: viewModel?.coordinate.latitude, longitude: viewModel?.coordinate.longitude)

代替：

let destCoordinates = CLLocationCoordinate2D(latitude: 38.420183, longitude: 27.205559)

我得到的纬度和经度值为nil或零。

let sourcePlaceMark = MKPlacemark(coordinate: sourceCoordinates!)
let destPlaceMark = MKPlacemark(coordinate: destCoordinates)

let sourceItem = MKMapItem(placemark: sourcePlaceMark)
let destItem = MKMapItem(placemark: destPlaceMark)

let directionRequest = MKDirections.Request()
directionRequest.source = sourceItem
directionRequest.destination = destItem
directionRequest.transportType = .automobile

let directions = MKDirections(request: directionRequest)
directions.calculate(completionHandler: {response, error in
guard let response = response else {
 if error != nil {
 print("Something went wrong!")
  }
 return
    }
 let route = response.routes[0]
 self.detailsFoodView?.mapView?.addOverlay(route.polyline, level: .aboveRoads)

 let rect = route.polyline.boundingMapRect
      self.detailsFoodView?.mapView?.setRegion(MKCoordinateRegion(rect), animated: true) 

预期结果是当前用户位置，从蓝点地标到带红线的红点地标，如您在屏幕截图中所见。

图片：