从 UIViewController 更改 SwiftUI 文本

Question

I'm quite new to Swift and absolute new to SwiftUI. I'm trying to combine UIViewController Google Maps and modern SwiftUI. In SwiftUI i have a few Text objects, and I want my GmapsController class to be able to modify these Text values, and redraw SwiftUI struct.

My main struct:

var _swiftUIStruct : swiftUIStruct = swiftUIStruct() // to have access in GmapsController
struct GoogMapView: View {
    var body: some View {
        let gmap = GmapsControllerRepresentable()
        return  ZStack {
            gmap
            _swiftUIStruct
        }
    }
}

UIViewControllerRepresentable wrapper of GmapsController :

struct GmapsControllerRepresentable: UIViewControllerRepresentable {
    func makeUIViewController(context: UIViewControllerRepresentableContext<GmapsControllerRepresentable>) -> GmapsController {
        return GmapsController()
    }
    func updateUIViewController(_ uiViewController: GmapsController, context: UIViewControllerRepresentableContext<GmapsControllerRepresentable>) {}
}

The GmapsController itself:

class GmapsController: UIViewController, CLLocationManagerDelegate, GMSMapViewDelegate {
    var locationManager = CLLocationManager()
    var mapView: GMSMapView!

    override func viewDidLoad() {
        super.viewDidLoad()

        locationManager.requestWhenInUseAuthorization()
        locationManager.delegate = self

        let camera = GMSCameraPosition.camera(
            withLatitude: (locationManager.location?.coordinate.latitude)!,
            longitude: (locationManager.location?.coordinate.longitude)!,
            zoom: 15
        )

        mapView = GMSMapView.map(withFrame: view.bounds, camera: camera)
        mapView.delegate = self
        self.view = mapView
    }

// HERE I WANT TO CHANGE SOME swiftUIStruct Text FIELDS

// calls after map move
    func mapView(_ mapView: GMSMapView, idleAt сameraPosition: GMSCameraPosition) {
        _swiftUIStruct.someTxt = "I hope this will work" // compilation pass, but value doesn't change
    }
}

And the swiftUIStruct struct:

struct swiftUIStruct {
    @State var someTxt = ""
    var body: some View {
        Text(someTxt) // THE TEXT I WISH I COULD CHANGE
    }
}

Googling this a whole day just made me feel dumb, any help is appreciated.

Answer 1

I hope my example code helps. Basically, move the model data outside, and pass it along, and change it. If you run this code, you will see the text "I hope this will work", NOT "Initial Content".

import SwiftUI

class ViewModel: ObservableObject {
  @Published var someTxt = "Initial Content"
}

struct ContentView: View {
  @ObservedObject var viewModel = ViewModel()

  var body: some View {
    ZStack {
      GoogleMapsView(viewModel: viewModel)
      Text(viewModel.someTxt)
    }
  }
}

struct GoogleMapsView: UIViewControllerRepresentable {
  var viewModel: ViewModel

  func makeUIViewController(context: Context) -> GmapsController {
    let controller = GmapsController()
    controller.viewModel = viewModel
    return controller
  }
  func updateUIViewController(_ uiViewController: GmapsController, context: Context) {}
}

class GmapsController: UIViewController {
  var viewModel: ViewModel?

  override func viewDidLoad() {
    viewModel?.someTxt = "I hope this will work"
  }
}

struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
    return ContentView()
  }
}