All of the code is in the SwiftUI tutorial at the URL provided above. Start with the BuildingListsAndNavigation.xcodeproj in the Complete folder of the downloaded project. I have just now repeated the changes shown above starting with a new download, with the same results. Note that the addition goes before the View, which is completely replaced.

The complete MapView.swift with all of the changes noted above, which are the only changes to the downloaded project identified above: import SwiftUI import MapKit struct MapView: View {     var coordinate: CLLocationCoordinate2D     @State private var region = MKCoordinateRegion()     struct Place: Identifiable {         let id = UUID()         let name: String         let coordinate: CLLocationCoordinate2D     }     var annotations = [         Place(name: "Xyz", coordinate: CLLocationCoordinate2D(latitude: coordinate.latitude, longitude: coordinate.longitude))     ]     var body: some View {         Map(coordinateRegion: $region, annotationItems: annotations) {             MapPin(coordinate: $0.coordinate)         }         .onAppear {             setRegion(coordinate)         }     }     private func setRegion(_ coordinate: CLLocationCoordinate2D) {         region = MKCoordinateRegion(             center: coordinate,             span: MKCoordinateSpan(latitudeDelta: 0.2, longitudeDelta: 0.2)         )     } } struct MapView_Previews: PreviewProvider {     static var previews: some View {         MapView(coordinate: CLLocationCoordinate2D(latitude: 34.011_286, longitude: -116.166_868))     } }

Nice fix for this problem. The purpose of this example was getting the .onChange to work correctly to call a function for selecting multiple values. Thanks for the help.