struct ContentView: View {
   @State private var title = "Default Name"
   @State private var numberInput = ""

   var body: some View {
      VStack(spacing: 10) {
         Text(title)
            .padding()
            .background(Color.yellow)
         TextField("Insert Number", text: $numberInput)
            .textFieldStyle(.roundedBorder)
            .padding(4)
            .keyboardType(.numbersAndPunctuation)
            .onChange(of: numberInput, initial: false) { old, value in
               if !value.isEmpty && Int(value) == nil {
                     numberInput = old
               }
            }
         HStack {
            Spacer()
            Button("Save") {
               title = numberInput
               numberInput = ""
            }
         }
         Spacer()
      }.padding()
   }
}