SwiftUI TextField which only accepts integers and binds to an Int? instead of a String

IntegerTextField.swift

import SwiftUI

private class IntegerTextFieldValue: ObservableObject {
    @Published var value = "" {
        didSet {
            let numbersOnly = value.filter { $0.isNumber }
            if value != numbersOnly {
                value = numbersOnly
            }
        }
    }
}

struct IntegerTextField: View {
    @Binding var value: Int?
    @StateObject private var fieldValue = IntegerTextFieldValue()

    var placeholder = ""

    var body: some View {
        TextField(placeholder, text: $fieldValue.value)
            .keyboardType(.numberPad)
            .onChange(of: fieldValue.value) { value = Int($0) }
            .onAppear {
                if let value = value {
                    fieldValue.value = "\(value)"
                }
            }
    }
}

struct NumericTextField_Previews: PreviewProvider {
    static var previews: some View {
        IntegerTextField(value: .constant(17))
            .textFieldStyle(RoundedBorderTextFieldStyle())
            .padding()
    }
}