MapKit for SwiftUI 无法将 MapPolyline 封装在 Bool 控件中

Question

在使用 MKRoutes 制作折线的 SwiftUI iOS 17 应用程序的 MapKit 中，我想在绘制路线时将 ProgressView 放置在地图顶部（并在完成之前禁用任何其他用户交互）。看来 MapPolyline() 函数需要位于 Map 闭包中，并且不能在外部进行重构，但我尝试将其包装在任务或 if 语句中的任何操作都失败了。

这是演示的简化版本：

struct ContentView: View {

    @State private var routes = [MKRoute]()
    @State private var showProgress: Bool = false

    var body: some View {
        ZStack {
            Map() {
            
                //want to start a ProgressView here
                if routes.count >= 1 {
                    ForEach(routes, id: \.self) { r in
                        MapPolyline(r)
                            .stroke(.blue, lineWidth: 4)
                    }
                }// if routes
                //want to end a ProgressView here
            
            }
            .onAppear {
                makeSomeRoutes()
            }
            if showProgress {
                ProgressView()
                    .tint(.red)
                    .scaleEffect(4)
            }
        }//z
    }//body

    func makeSomeRoutes() {
    
        let lats: [CLLocationDegrees] = [
            37.338207,
            38.5816,
            39.1677,
            40.760780
        ]
    
        let longs: [CLLocationDegrees] = [
            -121.886330,
             -121.4944,
             -120.1452,
             -111.891045
        ]

        for r in 0..<3 {
            let request = MKDirections.Request()
            request.source = MKMapItem(placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: lats[r], longitude: longs[r])))
            request.destination = MKMapItem(placemark: MKPlacemark(coordinate: CLLocationCoordinate2D(latitude: lats[r + 1], longitude: longs[r + 1])))
        
            Task {
                let result = try? await MKDirections(request: request).calculate()
                let aRoute = result?.routes.first
            
                if let aRoute {
                    self.routes.append(aRoute)
                }
            }
        }//for
    }//make some routes

}//struct

任何指导将不胜感激。 Xcode 15、iOS 17

Answer 1

您可以尝试使用

Annotation

来握住

ProgressView

。

// for testing, adjust accordingly
let center = CLLocationCoordinate2D(latitude: 39.1677, longitude: -120.1452)

var body: some View {
    ZStack {
        Map() {
            if routes.count >= 1 {
                ForEach(routes, id: \.self) { r in
                    MapPolyline(r).stroke(.blue, lineWidth: 8)
                }
            } else {
                Annotation("", coordinate: center) {
                    ProgressView().tint(.red).scaleEffect(4)
                }
            }
        }
    }
    .onAppear {
        makeSomeRoutes()
    }
}//body