我有一个从Google API加载注释的地图，当地图最初加载所有注释时，它们被'放置'，通过控制台的打印看到，但是它们不会显示在地图上，直到我移动地图一次。有人知道我是否需要调用一个方法来更新地图后放置注释?
struct ContentView: View {
var locationSearch = LocationSearch()
@State private var mapView = MapView()
@State var region = MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: -33.7944, longitude: 151.2649), span: MKCoordinateSpan(latitudeDelta: 0.015, longitudeDelta: 0.015))
@EnvironmentObject var sheetManager: SheetManager
var body: some View {
mapView
.popup(with: SheetManager())
.frame(width: UIScreen.screenWidth, height: UIScreen.screenHeight)
}
}
struct MapView: UIViewRepresentable {
@State var region = MKCoordinateRegion(center: CLLocationCoordinate2D(latitude: -33.7944, longitude: 151.2649), span: MKCoordinateSpan(latitudeDelta: 0.015, longitudeDelta: 0.015))
func updateUIView(_ uiView: MKMapView, context: Context) {
print("FLF: MapView updated")
uiView.setNeedsDisplay()
}
var locationManager = CLLocationManager()
let mapView = MKMapView(frame: CGRect(x: 0, y: 0, width: UIScreen.screenWidth, height: UIScreen.screenHeight))
func setupManager() {
locationManager.desiredAccuracy = kCLLocationAccuracyBest
locationManager.requestWhenInUseAuthorization()
locationManager.requestAlwaysAuthorization()
}
func makeUIView(context: Context) -> MKMapView {
setupManager()
mapView.region = ContentView().region
mapView.showsUserLocation = true
mapView.userTrackingMode = .follow
mapView.delegate = context.coordinator // set the delegate to the coordinator
placeMarkersForRegion(region: region)
return mapView
}
func placeMarkersForRegion(region: MKCoordinateRegion) {
var locationSearch = LocationSearch()
locationSearch.performSearch(region: region) { venues in
print("FLF: Placing (venues.count) marker(s)")
for marker in venues {
let annotation = MKPointAnnotation()
annotation.coordinate = marker.location
annotation.title = marker.name
mapView.addAnnotation(annotation)
}
}
}
func makeCoordinator() -> MapViewCoordinator {
MapViewCoordinator(self) // pass self to the coordinator so it can call `regionDidChangeAnimated`
}
func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
// Use the 'coordinate' property to get the current location of the map view
let currentRegion = mapView.region
print("FLF: Map has moved")
self.placeMarkersForRegion(region: currentRegion)
// Do something with the current region (e.g. update a state variable or perform a search)
}
}
class MapViewCoordinator: NSObject, MKMapViewDelegate {
var parent: MapView // add a property to hold a reference to the parent view
init(_ parent: MapView) {
self.parent = parent
}
func mapView(_ mapView: MKMapView, regionDidChangeAnimated animated: Bool) {
// Call the parent's implementation of this method
parent.mapView(mapView, regionDidChangeAnimated: animated)
}
func mapView(_ mapView: MKMapView, didSelect view: MKAnnotationView) {
view.canShowCallout = true
view.rightCalloutAccessoryView = UIButton(type: .detailDisclosure)
// Get the tapped annotation
guard let annotation = view.annotation else { return }
// Print the title of the annotation
print(annotation.title ?? "Unknown")
}
func mapView(_ mapView: MKMapView, annotationView view: MKAnnotationView, calloutAccessoryControlTapped control: UIControl) {
print("FLF: Marker tapped")
}
}
UIViewRepresentable和Coordinator未正确实现。例如，makeUIView必须初始化它，但您将其初始化为结构体上的属性，这将立即丢失。MapViewCoordinator(self)也是一个错误，因为self，即结构体，在SwiftUI更新后立即被忽略。
另一个问题是@State不应该持有一个视图，就像你的ContentView有@State的MapView。
下面是如何使用MKMapView和UIViewRepresentable的例子:
struct MKMapViewRepresentable: UIViewRepresentable {
@Binding var userTrackingMode: MapUserTrackingMode
func makeCoordinator() -> Coordinator {
Coordinator()
}
func makeUIView(context: Context) -> MKMapView {
context.coordinator.mapView
}
func updateUIView(_ uiView: MKMapView, context: Context) {
// MKMapView has a strange design that the delegate is called when setting manually so we need to prevent an infinite loop
context.coordinator.userTrackingModeChanged = nil
uiView.userTrackingMode = userTrackingMode == .follow ? MKUserTrackingMode.follow : MKUserTrackingMode.none
context.coordinator.userTrackingModeChanged = { mode in
userTrackingMode = mode == .follow ? MapUserTrackingMode.follow : MapUserTrackingMode.none
}
}
class Coordinator: NSObject, MKMapViewDelegate {
lazy var mapView: MKMapView = {
let mv = MKMapView()
mv.delegate = self
return mv
}()
var userTrackingModeChanged: ((MKUserTrackingMode) -> Void)?
func mapView(_ mapView: MKMapView, didChange mode: MKUserTrackingMode, animated: Bool) {
userTrackingModeChanged?(mode)
}
}
}