如何在iOS Swift的GoogleMaps中的CurrentLocation（locationStart）和SearchedLocation（locationEnd）之间绘制路线

Question

在我的代码中，我获取当前位置和搜索位置，但我无法在当前位置和搜索位置之间绘制路线。虽然我正在录制findRoutrButton我甚至使用了我的错误

DispatchQueue.main.async {}

错误：由于未捕获的异常'GMSThreadException'而终止应用程序，原因是：'必须从主线程调用API方法'

请帮我解决一下我的错误。

以下是我的总代码

import UIKit
import GoogleMaps
import GooglePlaces
import CoreLocation

enum Location {
case currentLocation
case destinationLocation
}

class ViewController: UIViewController, GMSMapViewDelegate, CLLocationManagerDelegate {

@IBOutlet weak var googleMapView: GMSMapView!
@IBOutlet weak var destinationTextfield: UITextField!

var locationManager = CLLocationManager()// for current location
var locationSelected = Location.currentLocation

var locationStart = CLLocation()
var locationEnd = CLLocation()

override func viewDidLoad() {
    super.viewDidLoad()

    //Your map initiation code
    self.googleMapView?.isMyLocationEnabled = true
    //Location Manager code to fetch current location
    locationManager.delegate = self
    locationManager.startUpdatingLocation()
}

//Location Manager delegates
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {

    let location = locations.last

    let camera = GMSCameraPosition.camera(withLatitude: (location?.coordinate.latitude)!, longitude: (location?.coordinate.longitude)!, zoom: 15.0)
    self.googleMapView?.animate(to: camera)
    print("user latitude = \(location?.coordinate.latitude)")
    print("user longitude = \(location?.coordinate.longitude)")

    locationStart = CLLocation(latitude: (location?.coordinate.latitude)!, longitude: (location?.coordinate.longitude)!)

    //Finally stop updating location otherwise it will come again and again in this delegate
    self.locationManager.stopUpdatingLocation()
    self.googleMapView.settings.myLocationButton = true
}

  func drawPath(currentLocation: CLLocation, searchedLocation: CLLocation)
  {

    let origin = "\(currentLocation.coordinate.latitude),\(currentLocation.coordinate.longitude)"
    let destination = "\(searchedLocation.coordinate.latitude),\(searchedLocation.coordinate.longitude)"

    let urlString = "https://maps.googleapis.com/maps/api/directions/json?origin=\(origin)&destination=\(destination)&mode=driving&key=APIKEY"

    let url = URL(string: urlString)
    URLSession.shared.dataTask(with: url!, completionHandler: {
        (data, response, error) in
        if(error != nil){
            print("error")
        }else{
            do{
                let json = try JSONSerialization.jsonObject(with: data!, options:.allowFragments) as! [String : AnyObject]
                let routes = json["routes"] as! NSArray
                self.googleMapView.clear()

                OperationQueue.main.addOperation({

                    DispatchQueue.main.async
                        {
                            for route in routes
                            {
                                DispatchQueue.main.async
                                    {
                                let routeOverviewPolyline:NSDictionary = (route as! NSDictionary).value(forKey: "overview_polyline") as! NSDictionary
                                let points = routeOverviewPolyline.object(forKey: "points")
                                let path = GMSPath.init(fromEncodedPath: points! as! String)
                                let polyline = GMSPolyline.init(path: path)
                                polyline.strokeWidth = 3

                                let bounds = GMSCoordinateBounds(path: path!)
                                self.googleMapView!.animate(with: GMSCameraUpdate.fit(bounds, withPadding: 30.0))

                                polyline.map = self.googleMapView
                                }
                            }   
                    }

                })
            }catch let error as NSError{
                print("error:\(error)")
            }
        }
    }).resume()
}
//for searching destination
@IBAction func destinationButton(_ sender: Any) {

    let autoCompleteController = GMSAutocompleteViewController()
    autoCompleteController.delegate = self

    locationSelected = .destinationLocation

    // Change text color
    UISearchBar.appearance().setTextColor(color: UIColor.black)
    self.locationManager.stopUpdatingLocation()

    self.present(autoCompleteController, animated: true, completion: nil)

    }
//finding route button
@IBAction func findRoutrButton(_ sender: Any) {

    DispatchQueue.main.async
              {
        self.drawPath(currentLocation: self.locationStart, searchedLocation: self.locationEnd)
              }
       }
}

Answer 1

在Google地图上绘制两个标记之间的折线

func getPolylineRoute(from source: CLLocation, to destination: CLLocation){

        let config = URLSessionConfiguration.default
        let session = URLSession(configuration: config)

        let url = URL(string: "http://maps.googleapis.com/maps/api/directions/json?origin=\(source.latitude),\(source.longitude)&destination=\(destination.latitude),\(destination.longitude)&sensor=false&mode=driving")!

        let task = session.dataTask(with: url, completionHandler: {
            (data, response, error) in
            if error != nil {
                print(error!.localizedDescription)
            }else{
                do {
                    if let json : [String:Any] = try JSONSerialization.jsonObject(with: data!, options: .allowFragments) as? [String: Any]{

                        let routes = json["routes"] as? [Any]
                    let overview_polyline = routes?[0] as?[String:Any]
                    let polyString = overview_polyline?["overview_polyline"] as?[String:Any]
                    let points = polyString?["points"] as? String
                        //draw polyline on map 
                        let path = GMSPath(fromEncodedPath: points!)
                        let polyline = GMSPolyline(path: path)
                        polyline.strokeWidth = 3.0
                        polyline.map = mapView // Your map view

                    }

                }catch{
                    print("error in JSONSerialization")
                }
            }
        })
        task.resume()
    }