SwiftUI: UIAlertController's textField does not responding in UIAlertAction - ios

Question

I need to use UIAlertContoller, as SwiftUI's Alert does not support TextField.
I must not use Custom created AlertView, due to various reason(Accessibility, DynamicType, Dark Mode support etc).
Basic Idea is, SwiftUI's alert must hold TextField & entered text must be reflect back for usage.
I created a SwiftUI view by Conforming to UIViewControllerRepresentable following is working code.
struct AlertControl: UIViewControllerRepresentable {
typealias UIViewControllerType = UIAlertController
#Binding var textString: String
#Binding var show: Bool
var title: String
var message: String
func makeUIViewController(context: UIViewControllerRepresentableContext<AlertControl>) -> UIAlertController {
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
alert.addTextField { textField in
textField.placeholder = "Enter some text"
}
let cancelAction = UIAlertAction(title: "cancel", style: .destructive) { (action) in
self.show = false
}
let submitAction = UIAlertAction(title: "Submit", style: .default) { (action) in
self.show = false
}
alert.addAction(cancelAction)
alert.addAction(submitAction)
return alert
}
func updateUIViewController(_ uiViewController: UIAlertController, context: UIViewControllerRepresentableContext<AlertControl>) {
}
func makeCoordinator() -> AlertControl.Coordinator {
Coordinator(self)
}
class Coordinator: NSObject, UITextFieldDelegate {
var control: AlertControl
init(_ control: AlertControl) {
self.control = control
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if let text = textField.text {
self.control.textString = text
}
return true
}
}
}
// SwiftUI View in some content view
AlertControl(textString: self.$text,
show: self.$showAlert,
title: "Title goes here",
message: "Message goes here")
Problem:
There is No activity in Alert Action when it is tapped. I put breakpoints to check, but it never hit there.
Even UITextFieldDelegate's function never hit.
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool
Edit: cancelAction or submitAction does not triggers on tap of these fields.

Answer 1

Here is full demo module for solution that works. Tested with Xcode 11.4 / iOS 13.4
See also important comments inline
struct AlertControl: UIViewControllerRepresentable {
#Binding var textString: String
#Binding var show: Bool
var title: String
var message: String
func makeUIViewController(context: UIViewControllerRepresentableContext<AlertControl>) -> UIViewController {
return UIViewController() // holder controller - required to present alert
}
func updateUIViewController(_ viewController: UIViewController, context: UIViewControllerRepresentableContext<AlertControl>) {
guard context.coordinator.alert == nil else { return }
if self.show {
let alert = UIAlertController(title: title, message: message, preferredStyle: .alert)
context.coordinator.alert = alert
alert.addTextField { textField in
textField.placeholder = "Enter some text"
textField.text = self.textString // << initial value if any
textField.delegate = context.coordinator // << use coordinator as delegate
}
alert.addAction(UIAlertAction(title: "cancel", style: .destructive) { _ in
// your action here
})
alert.addAction(UIAlertAction(title: "Submit", style: .default) { _ in
// your action here
})
DispatchQueue.main.async { // must be async !!
viewController.present(alert, animated: true, completion: {
self.show = false // hide holder after alert dismiss
context.coordinator.alert = nil
})
}
}
}
func makeCoordinator() -> AlertControl.Coordinator {
Coordinator(self)
}
class Coordinator: NSObject, UITextFieldDelegate {
var alert: UIAlertController?
var control: AlertControl
init(_ control: AlertControl) {
self.control = control
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
if let text = textField.text as NSString? {
self.control.textString = text.replacingCharacters(in: range, with: string)
} else {
self.control.textString = ""
}
return true
}
}
}
// Demo view for Alert Controll
struct DemoAlertControl: View {
#State private var text = ""
#State private var showAlert = false
var body: some View {
VStack {
Button("Alert") { self.showAlert = true }
.background(AlertControl(textString: self.$text, show: self.$showAlert,
title: "Title goes here", message: "Message goes here"))
Text(self.text)
}
}
}