ios - Swift/iOS 项目地图无法正确显示位置

Question

大家好，我在测试 Swift App 中的地图实现遇到问题。所以我添加了地图视图，就像在下面的代码中一样，然后作为预览数据，我传递了一个随机城市的坐标。然后我运行实时预览，并且（非常失望）看到蓝色矩形而不是地图。我搞砸了什么？

import MapKit
    struct MapSection: View {
        private var log: Log?
        
        @State var region: MKCoordinateRegion = MKCoordinateRegion()
        private var locationCoordinate: CLLocationCoordinate2D?
        
        init(_ log: Log) {
            self.log = log
            if let coordinate = log.location?.coordinate {
                let locationCoordinate = CLLocationCoordinate2D(latitude: coordinate.latitude, longitude: coordinate.longitude)
                self.locationCoordinate = locationCoordinate
                self.region = MKCoordinateRegion(center: locationCoordinate, span: MKCoordinateSpan(latitudeDelta: 0.075, longitudeDelta: 0.075))
            } else {
                self.log = nil
                self.locationCoordinate = nil
            }
        }
        
        var body: some View {
            Section(header: Text("Position on map")) {
                if log != nil && locationCoordinate != nil {
                    Map(coordinateRegion: $region, annotationItems: [self.log!]) {
                        _ in MapPin(coordinate: locationCoordinate!)
                    }
                        .frame(minHeight: 500)
                }
                else {
                    HStack {
                        Spacer()
                        Text("Map Error: Position Unknown")
                        Spacer()
                    }
                }
            }
        }
    }

struct LogDetail_Previews: PreviewProvider {
    static var previews: some View {
        let context = PersistenceController.preview.container.viewContext
        let log = Log(context: context)
        log.country = Locale.current.regionCode
        log.date = Date(timeIntervalSince1970: TimeInterval(100000))
        log.location = CLLocation(latitude: CLLocationDegrees(52.229676), longitude: CLLocationDegrees(21.012229))
        return LogDetail(log)
    }
}

标签： iosswiftswiftuimapkitmapkitannotation