MKOverlayRenderer 函数未被调用？

Question

import UIKit
import CoreData
import Foundation
import MapKit

struct Geoshape : Codable {
    let coordinates: [[Double]]
}
struct Field : Codable {
    let geo_shape: Geoshape
    let level_of_service: String
}
struct Record: Codable {
    let fields: Field
}

struct Verkeer: Codable{
    let records: Array<Record>
}



class ViewController: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate{
    var managedContext:NSManagedObjectContext?
    var coordinaten: [[[Double]]] = []
    var levels: [String] = []

    @IBOutlet weak var myMap: MKMapView!

    let initialLocation = CLLocation(latitude: 50.841890,  longitude: 4.323475)

    override func viewDidLoad() {
        super.viewDidLoad()

        myMap.delegate = self
        centerMapOnLocation(location: initialLocation)


    }

    @IBAction func clickRefresh(_ sender: Any) {
        //Refresh -> array leegmaken en waardes opnieuw toevoegen in core data
        coordinaten = []
        levels = []

        guard let url = URL(string: "https://opendata.brussels.be/api/records/1.0/search/?dataset=traffic-volume&rows=70&facet=level_of_service") else { return }
        let session = URLSession.shared
        let task = session.dataTask(with: url){ (data, response, error) in
            if let response = response {
                print(response)
            }
         if let data = data {
            let traffic = try? JSONDecoder().decode(Verkeer.self, from: data)
            let test = traffic?.records
            for loop in test! {

                //Coördinaten
                //print(loop.fields.geo_shape.coordinates)
                self.coordinaten.append(loop.fields.geo_shape.coordinates)

                //Levels
                //print(loop.fields.level_of_service)
                self.levels.append(loop.fields.level_of_service)
            }
            var points = [MKMapPoint]()
            for x in 0..<self.coordinaten.count{
                for y in 0..<self.coordinaten[x].count{
                    print(self.coordinaten[x][y][0])
                    let p = MKMapPoint(CLLocationCoordinate2DMake(self.coordinaten[x][y][0], self.coordinaten[x][y][1]))
                    points.append(p)
                }
                let polyline = MKPolyline(points: points, count: points.count)

                self.myMap.addOverlay(polyline)

                points.removeAll()
                print(points.count)
            }


            }
        }
        task.resume()

    }


    let regionRadius: CLLocationDistance = 200
    func centerMapOnLocation(location: CLLocation) {
        let coordinateRegion = MKCoordinateRegion(center: location.coordinate,
                                                  latitudinalMeters: regionRadius, longitudinalMeters: regionRadius)
        myMap.setRegion(coordinateRegion, animated: true)

        //Add pin
        let pin: MKPointAnnotation = MKPointAnnotation()
        pin.coordinate = CLLocationCoordinate2DMake(initialLocation.coordinate.latitude, initialLocation.coordinate.longitude);
        pin.title = "Current location"
        myMap.addAnnotation(pin)
    }

    func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer {
        if overlay is MKPolyline {
            let lineView = MKPolylineRenderer(overlay: overlay)
            lineView.strokeColor = UIColor.red
            lineView.lineWidth = 10
            return lineView
        }
        return MKOverlayRenderer()
    }

}

所以我一直试图在我的地图上显示一些坐标，但它似乎不起作用。我从 json 文件中获取坐标并打印它们没有问题，但它是我尝试将它们添加到我的地图的部分。任何人都知道为什么这个 "func mapView(_ mapView: MKMapView, rendererFor overlay: MKOverlay) -> MKOverlayRenderer" 没有被调用？当我在网上搜索时，我唯一能找到的是在 viewDidLoad() 函数中添加地图委托，但这对我也不起作用..

Answer 1

这是因为您的叠加层不可见，因为纬度和经度是向后的。交换它们，您将开始看到您的叠加层：

let coordinate = CLLocationCoordinate2DMake(self.coordinaten[x][y][1], self.coordinaten[x][y][0])

MKOverlayRenderer 函数未被调用？

MKOverlayRenderer function not being called?

swift

mkmapview

mkoverlay