title: Cannot assign to property: '$text' is immutable
body: <p>I wanted to make a custom textfield in SwiftUI to can handle first responder but I had this error in the code and struct is immutable I don't know what should I do?</p>
  
  <pre><code>struct CustomTextField: UIViewRepresentable {
  class Coordinator: NSObject, UITextFieldDelegate {
  
      @Binding var text: String
      var didBecomeFirstResponder = false
  
      init(txt: Binding&lt;String&gt;) {
          self.$text = txt
      }
  
      func textFieldDidChangeSelection(_ textField: UITextField) {
          text = textField.text ?? ""
      }
  
  }
  
  @Binding var text: String
  var isFirstResponder: Bool = false
  
  func makeUIView(context: UIViewRepresentableContext&lt;CustomTextField&gt;) -&gt; UITextField {
      let textField = UITextField(frame: .zero)
      textField.delegate = context.coordinator
      return textField
  }
  
  func makeCoordinator() -&gt; CustomTextField.Coordinator {
      return Coordinator(txt: $text)
  }
  
  func updateUIView(_ uiView: UITextField, context: UIViewRepresentableContext&lt;CustomTextField&gt;) {
      uiView.text = text
      if isFirstResponder &amp;&amp; !context.coordinator.didBecomeFirstResponder  {
          uiView.becomeFirstResponder()
          context.coordinator.didBecomeFirstResponder = true
      }
  }
  }
  </code></pre>