我正在尝试使用MVVM-Pattern将SwiftUI和CoreLocation集成起来。我的LocationManager作为辅助程序工作得很好。但是我该如何更改我的LocationViewModel的属性呢?我在LocationViewModel中实现了我的LocationManager的@ObservedObject。这是我的问题所在。
我不知道如何实现可以在运行时更改属性的属性。我的LocationView中没有任何变化。通过按下按钮一次,一切正常。但是LocationViewModel必须在每次LocationManager更改时更改其属性。
总之,我想显示当前用户的位置。
我不知道如何实现可以在运行时更改属性的属性。我的LocationView中没有任何变化。通过按下按钮一次,一切正常。但是LocationViewModel必须在每次LocationManager更改时更改其属性。
总之,我想显示当前用户的位置。
// Location Manager as Helper
import Foundation
import CoreLocation
class LocationManager: NSObject, ObservableObject {
let locationManager = CLLocationManager()
let geoCoder = CLGeocoder()
@Published var location: CLLocation?
@Published var placemark: CLPlacemark?
override init() {
super.init()
self.locationManager.delegate = self
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
self.locationManager.requestWhenInUseAuthorization()
self.locationManager.startUpdatingLocation()
}
func geoCode(with location: CLLocation) {
geoCoder.reverseGeocodeLocation(location) { (placemark, error) in
if error != nil {
print(error!.localizedDescription)
} else {
self.placemark = placemark?.first
}
}
}
}
extension LocationManager: CLLocationManagerDelegate {
func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
guard let location = locations.first else { return }
DispatchQueue.main.async {
self.location = location
self.geoCode(with: location)
}
}
func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) {
// TODO
}
}
// Location Model
import Foundation
import CoreLocation
struct Location {
var location: CLLocation = CLLocation()
var placemark: CLPlacemark = CLPlacemark()
}
// Location View Model
import SwiftUI
import CoreLocation
class LocationViewModel: ObservableObject {
@ObservedObject var locationManager: LocationManager = LocationManager()
@Published var location: Location
init() {
self.location = Location()
}
}
// Location View
import SwiftUI
struct LocationView: View {
@ObservedObject var locationViewModel: LocationViewModel = LocationViewModel()
var body: some View {
VStack(alignment: .leading) {
Text("Latitude: \(self.locationViewModel.location.location.coordinate.latitude.description)")
Text("Longitude: \(self.locationViewModel.location.location.coordinate.longitude.description)")
}
}
}
struct LocationView_Previews: PreviewProvider {
static var previews: some View {
LocationView()
}
}
更新
现在,我已经设置好了我的MapView。
但是我怎么能接收到我的LocationManager
的数据呢?didUpdateLocations
方法在LocationManager
中工作。
所有我尝试做的事情都失败了。我想根据当前用户位置在我的MapView
上设置区域。在UIKit中很简单,但在SwiftUI中却非常棘手。
// Map View
import SwiftUI
import MapKit
struct MapView: UIViewRepresentable {
@ObservedObject var locationManager: LocationManager = LocationManager()
class Coordinator: NSObject, MKMapViewDelegate {
var parent: MapView
init(_ control: MapView) {
self.parent = control
}
}
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
func makeUIView(context: Context) -> MKMapView {
let mapView = MKMapView(frame: .zero)
mapView.delegate = context.coordinator
return mapView
}
func updateUIView(_ mapView: MKMapView, context: Context) {
mapView.showsUserLocation = true
}
}
struct MapView_Previews: PreviewProvider {
static var previews: some View {
MapView()
}
}