我怎样才能根据点击的地图注释显示不同的视图？

Question

我正在努力做到这一点，以便根据单击的地图注释显示不同的视图。我正在使用 navigationView 并且无法使目的地成为有条件的。

import MapKit
import SwiftUI
    
struct Location: Identifiable {
let id = UUID() 
let name: String 
let coordinate: CLLocationCoordinate2D 
let symbol: String
    } 
struct ContentView: View {
        @State private var mapRegion = MKCoordinateRegion (center: CLLocationCoordinate2D(latitude: 51.5, longitude: -0.12), span: MKCoordinateSpan (latitudeDelta: 0.2, longitudeDelta: 0.2))
let locations = [ Location (name: "Buckingham Palace", coordinate: CLLocationCoordinate2D(latitude:                                      
    51.508, longitude: -0.076),symbol: "house"), Location(name: "Tower of London", coordinate: CLLocationCoordinate2D(latitude: 57.919, longitude: 12.577), symbol: "key")
        ]
var body: some View { 
NavigationView { 
Map(coordinateRegion: $mapRegion, annotationItems: locations) { location in MapAnnotation(coordinate: location.coordinate) {
    
    NavigationLink ( destination:  if location.symbol == "house"{  View2()} else {View3()}
                    }) { 
    ZStack{
     Circle()
      .frame(width: 35, height: 35)
      .foregroundColor(.orange) 
    Image(systemName: location.symbol)
    .foregroundColor(.white)
                        }
    
    
                }
                }
                .onAppear {
     MKMapView.appearance().mapType = .satellite
                }
                .ignoresSafeArea()
            }
            .navigationViewStyle(.stack)
    
        }
    
    
    }
    
    struct ContentView_Previews: PreviewProvider { static var previews: some View { ContentView()
            }
    
        }

我试过在 navigationlink() 中使用 if 语句，但它不起作用。

Answer 1

您可以尝试这种不同的方法，使用

NavigationStack

，而不是弃用的 NavigationView，

Button

和

switch

在

navigationDestination

。对我来说效果很好。

struct Location: Identifiable {
    let id = UUID()
    let name: String
    let coordinate: CLLocationCoordinate2D
    let symbol: String
}

struct ContentView: View {
    
    @State private var mapRegion = MKCoordinateRegion (center: CLLocationCoordinate2D(latitude: 51.5, longitude: -0.12), span: MKCoordinateSpan (latitudeDelta: 0.2, longitudeDelta: 0.2))
    
    let locations = [
        Location(name: "Buckingham Palace", coordinate: CLLocationCoordinate2D(latitude: 51.501, longitude: -0.141), symbol: "house"),
        Location(name: "Tower of London", coordinate: CLLocationCoordinate2D(latitude: 51.508, longitude: -0.076), symbol: "key")
    ]
    
    @State private var path = NavigationPath()  // <-- here
    
    var body: some View {
        NavigationStack(path: $path) { // <-- here
            Map(coordinateRegion: $mapRegion, annotationItems: locations) { location in MapAnnotation(coordinate: location.coordinate) {
                Button(action: { path.append(location.symbol) }) {  // <-- here
                    ZStack {
                        Circle().frame(width: 55, height: 55).foregroundColor(.orange)
                        Image(systemName: location.symbol).foregroundColor(.white)
                    }
                }
            }
            }.onAppear {
                MKMapView.appearance().mapType = .satellite
            }
            .ignoresSafeArea()
            .navigationDestination(for: String.self) { val in  // <-- here
                switch val {
                    case "house": View2()
                    case "key": View3()
                    default: View1()
                }
            }
        }
        .navigationViewStyle(.stack)
    }

}

struct View1: View {
    var body: some View {
        Text("View1")
    }
}

struct View2: View {
    var body: some View {
        Text("View2")
    }
}

struct View3: View {
    var body: some View {
        Text("View3")
    }
}