Ios 如何使SwiftUI视图扩展可用空间？

我正在尝试使快捷界面视图扩展其可用空间。我有一个MapView，它使用MapKit在屏幕上显示地图。我希望这张地图能够扩大VStack中的可用空间。您可以看到它位于红色视图上方和搜索栏下方。如果我使红色视图的高度为100，则贴图视图将缩小。如果我没有在红色视图上设置高度，则地图视图会更大，但是红色视图看起来不像我想要的那样

我希望红色视图的高度为100，地图视图填充搜索栏下方和红色视图上方的所有可用高度

ContentView：

struct ContentView: View {

@ObservedObject
var viewModel: HomeViewModel

var body: some View {
    NavigationView {
        ZStack {
            ColorTheme.brandBlue.value.edgesIgnoringSafeArea(.all)
            VStack {
                CardView {
                    EditText(hint: "Search", text: self.$viewModel.searchText, textContentType: UITextContentType.organizationName)
                }
                MapView(annotations: self.$viewModel.restaurantAnnotations)
                    .cornerRadius(8)
                CardView(height: 100) {
                    HStack {
                        Color.red

                    }
                }
            }
        }
        .navigationBarTitle("", displayMode: .inline)
        .navigationBarHidden(true)
        .navigationBarBackButtonHidden(true)
    }
}
}

卡德维尤

struct CardView<Content>: View where Content : View {
var height: CGFloat = .infinity
var content: () -> Content
var body: some View {
    content()
        .padding(EdgeInsets.init(top: 0, leading: 8, bottom: 8, trailing: 8))
    .background(Color.white.cornerRadius(8))
        .shadow(radius: 2, x: 0, y: 1)
        .frame(minWidth: 0, maxWidth: .infinity, minHeight: 0, maxHeight: height)
}
}

地图视图

struct MapView: UIViewRepresentable {

@Binding
var annotations: [MKAnnotation]

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


func updateUIView(_ view: MKMapView, context: Context) {
    view.delegate = context.coordinator
    view.addAnnotations(annotations)
    if annotations.count == 1 {
        let coords = annotations.first!.coordinate
        let region = MKCoordinateRegion(center: coords, span: MKCoordinateSpan(latitudeDelta: 0.1, longitudeDelta: 0.1))
        view.setRegion(region, animated: true)
    }

}

func makeCoordinator() -> MapViewCoordinator {
    MapViewCoordinator(self)
}
}

MapViewCoordinator

class MapViewCoordinator: NSObject, MKMapViewDelegate {

var mapViewController: MapView

init(_ control: MapView) {
    self.mapViewController = control
}


func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView?{
    //Custom View for Annotation
    let identifier = "Placemark"
    if  let annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) {
        annotationView.annotation = annotation
        return annotationView
    } else {
        let annotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
        annotationView.isEnabled = true
        annotationView.canShowCallout = true
        let button = UIButton(type: .infoDark)
        annotationView.rightCalloutAccessoryView = button
        return annotationView
    }

    return nil
}
}

如您所见，地图视图没有填满可用空间

现在，所有可用空间都已填满，但红色视图高度不是100 以下是一个解决方案（使用Xcode 11.4测试）：

struct CardView:View其中Content:View{
变量高度：CGFloat？=nil//
class MapViewCoordinator: NSObject, MKMapViewDelegate {

var mapViewController: MapView

init(_ control: MapView) {
    self.mapViewController = control
}


func mapView(_ mapView: MKMapView, viewFor annotation: MKAnnotation) -> MKAnnotationView?{
    //Custom View for Annotation
    let identifier = "Placemark"
    if  let annotationView = mapView.dequeueReusableAnnotationView(withIdentifier: identifier) {
        annotationView.annotation = annotation
        return annotationView
    } else {
        let annotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
        annotationView.isEnabled = true
        annotationView.canShowCallout = true
        let button = UIButton(type: .infoDark)
        annotationView.rightCalloutAccessoryView = button
        return annotationView
    }

    return nil
}
}

struct CardView<Content>: View where Content : View {
    var height: CGFloat? = nil // << here !!