Problem of resizing Map using SwiftUI Mapkit

Question

I would like to zoom in my map on the application, I tried both using latitudinalMeters: 300, longitudinalMeters: 300 or spin with latitudeDelta: 0.001. Both of them did not work at all.

I also chose (0, 0) as my center, but every time I run on the simulator, I have (37.326010,-122.026056) as my center. Apparently, none of the default settings of center and region that I had set in my location manager works in ContentView.

Here is my code of LocationManager.swift:

import Foundation
import CoreLocation
import MapKit

class LocationManager: NSObject, ObservableObject{
    let locationManager = CLLocationManager()
    
    @Published var location: CLLocation?
    @Published var region: MKCoordinateRegion
    
    override init(){
        self.region = MKCoordinateRegion(center: CLLocationCoordinate2D.init(latitude: 0,longitude: 0),latitudinalMeters: 300, longitudinalMeters: 300)
        super.init()
        self.locationManager.delegate = self
        self.locationManager.desiredAccuracy = kCLLocationAccuracyBest
        self.locationManager.requestWhenInUseAuthorization()
        self.locationManager.startUpdatingLocation()
    }
}


extension LocationManager : CLLocationManagerDelegate {
    func locationManager(_ manager: CLLocationManager,
                         didUpdateLocations locations: [CLLocation]){
        guard let location = locations.last else { return }
        self.region = MKCoordinateRegion(center: location.coordinate, latitudinalMeters: 300, longitudinalMeters: 300)
        self.location = location
    }
}

Here is my ContentView:

struct ContentView: View {
    var body: some View {
        MapView2()
    }
}

struct MapView2: View {
    
    @ObservedObject var locationManager = LocationManager()
    
    var body: some View {
        let coord = locationManager.location?.coordinate
        let lat = coord?.latitude ?? 0
        let lon = coord?.longitude ?? 0
        return VStack {
            Map(coordinateRegion: $locationManager.region,
                interactionModes: .all,
                showsUserLocation: true, userTrackingMode: .constant(.follow))
        }
    }
}

user_10408494 · Answer

As for SwiftUI using MapKit, I would not use the CoreLocation framework. You can use the .onChange modifier to perform zoom changes to your View. You can use the @State var zoom with a SwiftUI gesture to perform them if you want, or anything that can do those changes live. I added two buttons within a slider to zoom in or out for the example.

import SwiftUI
import MapKit

struct ContentView: View {
  
  var body: some View {
    MapsView()
  }
}

struct MapsView: View {

  @State var zoom: CGFloat = 15

  @State var mapCoordinate = MKCoordinateRegion(
    center: CLLocationCoordinate2D(
      latitude: 38.989202809314854,
      longitude: -76.93626224283602),
    span: MKCoordinateSpan(
      latitudeDelta: .zero,
      longitudeDelta: .zero))

  var body: some View {
    VStack(spacing: 16) {

      Map(coordinateRegion: $mapCoordinate)
        .ignoresSafeArea(edges: .all)

      // You can see the changes being operating by the .onChange modifier.
      Slider(value: $zoom,
             in: 0.01...50,
             minimumValueLabel: Image(systemName: "plus.circle"),
             maximumValueLabel: Image(systemName: "minus.circle"), label: {})
        .padding(.horizontal)
        .onChange(of: zoom) { value in
          mapCoordinate.span.latitudeDelta = CLLocationDegrees(value)
          mapCoordinate.span.longitudeDelta = CLLocationDegrees(value)
        }
    }
    .font(.title)
  }
}

Problem of resizing Map using SwiftUI Mapkit

1 Answers