在 calloutAccessoryControlTapped 时更改传入 "MapView: UIViewRepresentable" 的 BindableObject 的值

Question

构建一个主要是 SwiftUI 的应用程序...我正在尝试将父视图中 BindableObject 的值连接（绑定）到 MapKit 子视图，这样当点击注释（标注附件）时（注释标签上的小 (i) 按钮...

...它将 $showDetails 的值更改为 true，它连接到 "sheet(isPresented: $showDetails...)" 进一步向上的视图层次结构，然后显示模态：

struct MapView: UIViewRepresentable {

    @Binding var mapSelected: Int
    @Binding var showDetails: Bool    // I WANT TO TOGGLE THIS WHEN CALLOUT ACCESSORY IS TAPPED

    @Binding var location: Location
    @Binding var previousLocation: Location

    @Binding var autoZoom: Bool
    @Binding var autoZoomLevel: Int

    class Coordinator: NSObject, MKMapViewDelegate {

        @Binding var showDetails: Bool

        init(showDetails: Binding<Bool>) {
            _showDetails = showDetails
        }

        func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
            guard let coordinates = view.annotation?.coordinate else { return }
            let span = mapView.region.span
            let region = MKCoordinateRegion(center: coordinates, span: span)
            mapView.setRegion(region, animated: true)
        }

        func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView? {
            guard let annotation = annotation as? LocationAnnotation else { return nil }
            let identifier = "Annotation"
            var annotationView: MKMarkerAnnotationView? = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) as? MKMarkerAnnotationView
            if annotationView == nil {
                annotationView = MKMarkerAnnotationView(annotation: annotation, reuseIdentifier: identifier)
                annotationView?.markerTintColor = UIColor(hex: "#00b4ffff")
                annotationView?.animatesWhenAdded = true
                annotationView?.canShowCallout = true
                annotationView?.rightCalloutAccessoryView = UIButton(type: .detailDisclosure)
            } else {
                annotationView?.annotation = annotation
            }
            return annotationView
        }

    func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
            guard let loc = view.annotation as? LocationAnnotation else {
                    print("sorry")
                    return
            }
            print(self.showDetails)     // true, false, true, false, ...
            self.showDetails.toggle()   // THIS DOES TOGGLE, BUT THE VALUE IS NOT OBSERVED BY THE PARENT VIEW
        }
    }

    func makeCoordinator() -> Coordinator {
        return Coordinator(showDetails: $showDetails)
    }

    func makeUIView(context: Context) -> MKMapView {
            let map = MKMapView()
            map.delegate = context.coordinator
            return map
    }

    func updateUIView(_ uiView: MKMapView, context: Context) {
            switch mapSelected {
                    case 0:
                            uiView.mapType = .standard
                    default:
                            uiView.mapType = .hybrid
            }
            let currentRegion = uiView.region  // get the current region
            var span: MKCoordinateSpan
            var center: CLLocationCoordinate2D
            var newRegion: MKCoordinateRegion

            if currentRegion.span.latitudeDelta == 90.0 && currentRegion.span.longitudeDelta == 180.0 {   // INITIAL
                    span = MKCoordinateSpan(latitudeDelta: 18.0, longitudeDelta: 18.0)
                    center = CLLocationCoordinate2D(latitude: 54.5, longitude: -110)
                    newRegion = MKCoordinateRegion(center: center, span: span)
                    uiView.setRegion(newRegion, animated: true)
            }
            updateAnnotations(from: uiView)
    }

   // ...
}

我期望的是，当点击 callout 附件时，showDetails 会切换（确实如此），但在父视图中看不到任何效果 — sheet 未显示。似乎绑定没有发布其新状态。

我错过了什么/做错了什么？我发现将 UIKit 与 SwiftUI 集成先是简单，然后是困难，然后是简单，然后是不可能。请帮忙！

Answer 1

事实证明，我看错地方了。问题不在于上面的代码（100% 没问题），而在于应该一直在监听 showDetails[= 的更改值的容器视图35=]，但不是因为我将 showDetails 传递给它的方式，例如

ContentView.swift

Footer(search: search, locationStore: self.locationStore, searchCoordinates: self.searchCoordinates, showDetails: self.showDetails) // NOT PASSED AS A BINDING...

Footer.swift

struct Footer: View { @EnvironmentObject var settingsStore: SettingsStore @ObservedObject var search: SearchTerm @ObservedObject var locationStore: LocationStore @ObservedObject var searchCoordinates: SearchCoordinates @State var showDetails: Bool // DECLARE LOCAL STATE, WILL NOT BE AWARE OF CHANGE TO showDetails FROM MapView

非常简单的修复：

ContentView.swift

Footer(search: search, locationStore: self.locationStore, searchCoordinates: self.searchCoordinates, showDetails: self.$showDetails)

Footer.swift

struct Footer: View { @EnvironmentObject var settingsStore: SettingsStore @ObservedObject var search: SearchTerm @ObservedObject var locationStore: LocationStore @ObservedObject var searchCoordinates: SearchCoordinates @Binding var showDetails: Bool

当不小心对传入变量使用错误的属性包装器时，感觉像这样的错误很容易在 SwiftUI 中遇到（顺便说一句，这很棒）。编译器不会警告您，也没有运行时错误，只是……什么也没有发生。而你和我一样，可能倾向于追逐红色鲱鱼a.k.a。完美的代码。

在 calloutAccessoryControlTapped 时更改传入 "MapView: UIViewRepresentable" 的 BindableObject 的值

Changing the value of a BindableObject passed into a "MapView: UIViewRepresentable" when calloutAccessoryControlTapped

uikit

mapkit

swift

swiftui