Read #Binding Value - swiftui

Question

I try to make custom textfield so I give it #Binding to response to the text value as showing below, The problem is when I try to detect the change of text its just response in the "Preview", But when run the app on the "Simulator" it doesn't response, I tried many different ways to solve this problem but nothing is work.
import SwiftUI
struct MyTextField: UIViewRepresentable {
typealias UIViewType = UITextField
#Binding var becomeFirstResponder: Bool
#Binding var text: String
var placeholder = ""
func makeUIView(context: Context) -> UITextField {
let textField = UITextField()
textField.translatesAutoresizingMaskIntoConstraints = false
textField.widthAnchor.constraint(equalToConstant: 320).isActive = true
textField.textColor = UIColor.systemBlue
textField.font = UIFont.boldSystemFont(ofSize: 22)
textField.textAlignment = .left
textField.keyboardType = .default
textField.minimumFontSize = 13
textField.adjustsFontSizeToFitWidth = true
textField.text = self._text.wrappedValue
textField.placeholder = self.placeholder
textField.delegate = context.coordinator
return textField
}
func updateUIView(_ textField: UITextField, context: Context) {
if self.becomeFirstResponder {
DispatchQueue.main.async {
textField.becomeFirstResponder()
self.becomeFirstResponder = false
}
}
}
func makeCoordinator() -> Coordinator {
Coordinator(parent: self)
}
class Coordinator: NSObject, UITextFieldDelegate {
var parent: MyTextField
init(parent: MyTextField) {
self.parent = parent
}
func textFieldShouldReturn(_ textField: UITextField) -> Bool {
textField.resignFirstResponder()
}
func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
let currentText = textField.text ?? ""
guard let stringRange = Range(range, in: currentText) else {
return false
}
let updateText = currentText.replacingCharacters(in: stringRange, with: string)
return updateText.count < 20
}
}
}
struct TextFieldFirstResponder: View {
#State private var becomeFirstResponder = false
#State private var text = "LLL"
private var placeholder = "Untitled"
var body: some View {
VStack {
ZStack(alignment: .trailing) {
MyTextField(becomeFirstResponder: self.$becomeFirstResponder, text: self.$text, placeholder: self.placeholder)
.frame(width: 343, height: 56, alignment: .leading)
.padding(EdgeInsets(top: 27, leading: 13, bottom: 0, trailing: 0))
.background(
RoundedRectangle(cornerRadius: 10, style: .continuous)
.fill(Color(UIColor.secondarySystemBackground))
.frame(width: 342, height: 56, alignment: .center)
)
.onAppear {
self.becomeFirstResponder = true
}
}
Text("\(self.$text.wrappedValue)") // <------ Do not read the "text"
}
}
}
struct TextFieldFirstResponder_Previews: PreviewProvider {
static var previews: some View {
TextFieldFirstResponder()
}
}

Answer 1

You don't need to use $ here, read property directly
Text(self.text) // <------ Do not use $
and I assume you wanted to update it via binding
let updateText = currentText.replacingCharacters(in: stringRange, with: string)
self.parent.text = updateText // << here !!
return updateText.count < 20
Tested & worked with Xcode 12.1 / iOS 14.1