Swiftui 使用mapViewDidChangeVisibleRegion和CLGeocoder返回国家名称

我只想返回黑色圆圈停止的国家的名称。 [1]: 上图中的示例

我知道这可以通过CLGeocoder和CLPlacemark以及Mapkit来完成，我已经尝试了很多，但总是出现错误，应用程序会崩溃

我的代码

import MapKit
import SwiftUI

struct MapView: UIViewRepresentable {
    
    @Binding var centralCoordinate: CLLocationCoordinate2D
    var anotations: [MKPointAnnotation]
    
    func makeUIView(context: Context) -> MKMapView{
        let mapview = MKMapView()
        mapview.delegate = context.coordinator
        return mapview
    }
    
    func updateUIView(_ view: MKMapView, context: Context) {
        
        if anotations.count != view.annotations.count {
            view.removeAnnotations(view.annotations)
            view.addAnnotations(anotations)
        }
    }
    
    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }
    
    class Coordinator: NSObject, MKMapViewDelegate {
        var parent: MapView
        
        init(_ parent: MapView) {
            self.parent = parent
        }
        
        func mapViewDidChangeVisibleRegion(_ mapView: MKMapView) {

            parent.centralCoordinate = mapView.centerCoordinate

            let geoCoder = CLGeocoder()
            let location = CLLocation(latitude: mapView.centerCoordinate.latitude, longitude: mapView.centerCoordinate.longitude)
            geoCoder.reverseGeocodeLocation(location, completionHandler: { (placemarks, error) -> Void in
                
                // Place details
                var placeMark: CLPlacemark!
                placeMark = placemarks?[1]
                // Country
                if let country = placeMark.country {
                    print(country)
                }
            })
        }
    }
}

extension MKPointAnnotation{
    static var eample: MKPointAnnotation {
        let annotaton = MKPointAnnotation()
        annotaton.title = "London"
        annotaton.subtitle = "Home TO 2012 Summer Olampics"
        annotaton.coordinate = CLLocationCoordinate2D(latitude: 51.5, longitude: -0.13)
        return annotaton
    }
}

struct MapView_Previews: PreviewProvider {
    static var previews: some View {
        MapView(centralCoordinate: .constant(MKPointAnnotation.eample.coordinate), anotations: [MKPointAnnotation.eample])
    }
}

我的视图代码

import  MapKit
import SwiftUI

struct MapViewIntegration: View {
    
    @State private var centercoordinate = CLLocationCoordinate2D()
    @State private var locations = [MKPointAnnotation]()
    
    var body: some View {
        ZStack {
            MapView(centralCoordinate: $centercoordinate,anotations: locations)
        .edgesIgnoringSafeArea(.all)
        Circle()
        .opacity(0.3)
        .frame(width: 32, height: 32)
            VStack{
                Spacer()
                HStack{
                    Spacer()
                    Button(action: {
                        let newLocations = MKPointAnnotation()
                           newLocations.coordinate = self.centercoordinate
                           self.locations.append(newLocations)
                    }) {
                        Image(systemName: "plus")
                    }.padding()
                    .background(Color.white)
                    .font(.title)
                    .clipShape(Circle())
                    .padding(.trailing)
                }
            }
        }
    }
}

struct MapViewIntegration_Previews: PreviewProvider {
    static var previews: some View {
        MapViewIntegration()
    }
}

请帮忙，

---

提前感谢

这个答案是由@SanzioAngeli给出的

将此代码替换为

   func mapViewDidChangeVisibleRegion(_ mapView: MKMapView) {

            parent.centralCoordinate = mapView.centerCoordinate

            let geoCoder = CLGeocoder()
            let location = CLLocation(latitude: mapView.centerCoordinate.latitude, longitude: mapView.centerCoordinate.longitude)
            geoCoder.reverseGeocodeLocation(location, completionHandler: { (placemarks, error) -> Void in
                
                // Place details
                var placeMark: CLPlacemark!
                placeMark = placemarks?[1]
                // Country
                if let country = placeMark.country {
                    print(country)
                }
            })
        }
    }

这个

@谢谢你

---

记住不要一次发送太多请求，所有请求都会失败并抛出致命错误。

这个答案由@SanzioAngeli给出

将此代码替换为

   func mapViewDidChangeVisibleRegion(_ mapView: MKMapView) {

            parent.centralCoordinate = mapView.centerCoordinate

            let geoCoder = CLGeocoder()
            let location = CLLocation(latitude: mapView.centerCoordinate.latitude, longitude: mapView.centerCoordinate.longitude)
            geoCoder.reverseGeocodeLocation(location, completionHandler: { (placemarks, error) -> Void in
                
                // Place details
                var placeMark: CLPlacemark!
                placeMark = placemarks?[1]
                // Country
                if let country = placeMark.country {
                    print(country)
                }
            })
        }
    }

这个

@谢谢你

---

记住不要一次发送太多请求，所有请求都会失败并抛出致命错误。

您的代码在哪里崩溃，您收到了什么错误消息？它在这行代码上崩溃“``如果let country=placeMark.country{print（country）}``说“线程1：致命错误：隐式展开可选值时意外发现nil”请尝试在该行之前打印每个值（placeMark，placeMark.country，country），以查看哪个值打印nil。这可能会缩小问题的范围。@SanzioAngeli placeMark返回nil so print（placeMark.country）引起crash@SanzioAngeli谢谢你的建议问题是当我移动地图时，它会向苹果服务器发送太多请求，请求会失败并抛出一个错误。非常感谢你的回答你的代码在哪里崩溃，你收到了什么错误消息？如果让country=placeMark.co，它会在这行代码上崩溃untry{print（country）}`saying“线程1：致命错误：隐式展开可选值时意外发现nil”尝试打印这些值中的每一个（placeMark，placeMark.country，country）就在那行之前，看看哪一行打印的是零。这可能会缩小问题的范围。@SanzioAngeli placeMark返回零所以打印（placeMark.country）引起crash@SanzioAngeli谢谢你的建议，问题是当我移动地图时，它会向苹果服务器发送太多请求，请求会失败并抛出错误。非常感谢你的回答