Code from "Designing an API Client in Swift"

EnvironmentPicker.swift

enum APIEnvironment: String, CaseIterable {
    case dev
    case test
    case stage
    case prod
}

struct ContentView: View {
    @State private var selection: APIEnvironment? = env
    
    var body: some View {
        List(selection: $selection) {
            ForEach(APIEnvironment.allCases, id: \.self, content: makeView)
        }
        .environment(\.editMode, .constant(EditMode.active))
        .navigationBarItems(trailing: Button("Save") {
            DebugSettings.shared.environment = selection!
            fatalError("Restarting the app")
        })
        .disabled(selection == nil)
        .navigationBarTitle("Environment")
    }
    
    private func makeView(for env: APIEnvironment) -> some View {
        VStack(alignment: .leading) {
            Text(env.rawValue)
                .font(.headline)
            Text(env.host)
                .font(.footnote)
                .foregroundColor(.secondary)
        }.tag(env)
    }
}