I set a variable swingPreviewLocation in .inAppear() but Swift forget’s it along the way. Printing the variable in the Map view returns nil.

However: Adding a Text() into the body, then Swift remembers and prints

▿ Optional<Location>
  ▿ some : Location
    - latitude : 48.026164457627125
    - longitude : 11.958078424370319

Code:

import SwiftUI
import MapKit

struct SwingDetailView: View {
    
    var swing: Swing
    
    @State var swingPreviewLocation: Location? // Location is a struct
    
    var body: some View {
        
        VStack {
            // This helps keep the variable. If I remove it, swift forgets the variable later.
            if let latitude = swingPreviewLocation?.latitude,
               let longitude = swingPreviewLocation?.longitude {
                Text("Latitude: (Int(latitude)), Longitude: (Int(longitude))")
            }
            
            Map () {
                let _ = print(self.swingPreviewLocation)
                if let location = self.swingPreviewLocation {
                    Annotation("Club", coordinate: CLLocation(latitude: location.latitude, longitude: location.longitude).coordinate) {
                        Text("C")
                    }
                }
            }
            .onAppear() {
                self.swingPreviewLocation = swing.location
            }
        }
    }
}

class Swing {
    let location: Location?
    init(location: Location?) {
        self.location = location
    }
}


struct Location {
    var latitude: Double
    var longitude: Double
}