Question

我在以芝加哥为中心的视图中有一张地图。我希望用户能够在地图上放置图钉/注释，然后检索这些坐标。该地图可以很好地加载芝加哥，但我无法使用注释代码。

我似乎找不到SwiftUI的答案。只有Swift和Storyboard。我觉得我有99％的代码，但各部分的位置不正确。我提供了错误所在的屏幕截图。感谢您的帮助。

import SwiftUI
import MapKit

struct EntireMapView: UIViewRepresentable {

    func updateUIView(_ mapView: MKMapView, context: Context) {

        mapView.delegate = context.coordinator

        let longPressGesture = UILongPressGestureRecognizer(target: mapView, action: #selector(EntireMapViewCoordinator.addAnnotation(gesture:)))
        mapView.addGestureRecognizer(longPressGesture)

        let span = MKCoordinateSpan(latitudeDelta: 0.3, longitudeDelta: 0.3)

        var chicagoCoordinate = CLLocationCoordinate2D()
        chicagoCoordinate.latitude = 41.878113
        chicagoCoordinate.longitude = -87.629799

        let region = MKCoordinateRegion(center: chicagoCoordinate, span: span)

        mapView.setRegion(region, animated: true)

    }

    func makeUIView(context: Context) -> MKMapView {

        let mapView = MKMapView(frame: .zero)
        mapView.delegate = context.coordinator
        return mapView

    }

    func makeCoordinator() -> EntireMapViewCoordinator {
        return EntireMapViewCoordinator(self)
    }

    class EntireMapViewCoordinator: NSObject, MKMapViewDelegate {

        var entireMapViewController: EntireMapView

        init(_ control: EntireMapView) {
          self.entireMapViewController = control
        }

        func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
            return (annotation as? MKAnnotationView)!
        }

        @objc func addAnnotation(gesture: UILongPressGestureRecognizer) {

            if gesture.state == .ended {

                let point = gesture.location(in: self.mapView) **<--- ERROR HERE**
                let coordinate = mapView.convert(point, toCoordinateFrom: mapView)

                var annotation = MKPointAnnotation()
                annotation.coordinate = coordinate

                self.mapView.addAnnotation(annotation) **<--- ERROR HERE**
            }
        }
    }
}

struct EntireMapView_Previews: PreviewProvider {
    static var previews: some View {
        EntireMapView()
    }
}

Here's a screen shot of the errors

Answer 1

我不知道您是否还在寻找答案。但是这里是一个。我为此问题付出了很多努力，我不知道我的答案是否正确，但是它对我有用，所以这里是：

@objc func addAnnotation(gesture: UITapGestureRecognizer){
   if let mapView = gestureRecognizer.view as? MKMApView{
      let point = gestureRecognizer.location(in: mapView) 
      let coordinate = mapView.convert(point, toCoordinateFrom: mapView) 
      let annotation = MKPointAnnotation() 
      annotation.coordinate = coordinate 
      DispatchQueue.main.async{
          mapView.addAnnotation(annotation)
        }
    }
}

如您所见，我使用的不是UILongPressGestureRecognizer，而是UITapGestureRecognize。

免责声明：我不知道这是否是最好的方法！半年前我才刚开始进行swift / swiftUI编程:)，这是我的第一个答案。

进一步的实现：您应该只收集数组中的所有注释，并从updateUIView方法中更新mapView。我在这里使用DispatchQueue.main.async时不知道我是否正确。但是每当我遇到Ui的变化时，我都认为您应该在主线程上完成

Screenshot with explanation

Answer 2

这是答案的完整代码。这主要归功于@yeezy，因为使用以下行获取视图：let mapView = gestureRecognizer.view as? MKMApView是该问题中的主要错误。

  struct EntireMapView: UIViewRepresentable {

        func updateUIView(_ mapView: MKMapView, context: Context) {

            let span = MKCoordinateSpan(latitudeDelta: 0.3, longitudeDelta: 0.3)
            var chicagoCoordinate = CLLocationCoordinate2D()
            chicagoCoordinate.latitude = 41.878113
            chicagoCoordinate.longitude = -87.629799
            let region = MKCoordinateRegion(center: chicagoCoordinate, span: span)
            mapView.setRegion(region, animated: true)

        }

        func makeUIView(context: Context) -> MKMapView {

            let myMap = MKMapView(frame: .zero)
            let longPress = UILongPressGestureRecognizer(target: context.coordinator, action: #selector(EntireMapViewCoordinator.addAnnotation(gesture:)))
            longPress.minimumPressDuration = 1
            myMap.addGestureRecognizer(longPress)
            myMap.delegate = context.coordinator
            return myMap

        }

    func makeCoordinator() -> EntireMapViewCoordinator {
        return EntireMapViewCoordinator(self)
    }

    class EntireMapViewCoordinator: NSObject, MKMapViewDelegate {

        var entireMapViewController: EntireMapView

        init(_ control: EntireMapView) {
          self.entireMapViewController = control
        }


        @objc func addAnnotation(gesture: UIGestureRecognizer) {

            if gesture.state == .ended {

                if let mapView = gesture.view as? MKMapView {
                let point = gesture.location(in: mapView)
                let coordinate = mapView.convert(point, toCoordinateFrom: mapView)
                let annotation = MKPointAnnotation()
                annotation.coordinate = coordinate
                mapView.addAnnotation(annotation)
                }
            }
        }
    }
}

Answer 3

我首先将mapView.delegate = context.coordinator从updateUIView中移除。在makeUIView（您已经在做）中，该操作只能执行一次。

如何让用户在地图上添加图钉并获取SwiftUI中的坐标？

3 个答案: