Swiftui 读取@Binding值

我尝试自定义textfield，所以我给它@Binding以响应如下所示的文本值，问题是当我尝试检测文本的变化时，它只是在“预览”中响应，但当在“模拟器”上运行应用程序时，它没有响应，我尝试了许多不同的方法来解决这个问题，但没有任何效果

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()
    }
}

导入快捷界面
结构MyTextField:UIViewRepresentable{
typealias UIViewType=UITextField
@绑定变量成为第一响应者：Bool
@绑定变量文本：字符串
var placeholder=“”
func makeUIView（上下文：context）->UITextField{
设textField=UITextField（）
textField.translatesAutoResizezingMaskintoConstraints=false
textField.widthAnchor.constraint（equalToConstant:320）.isActive=true
textField.textColor=UIColor.systemBlue
textField.font=UIFont.boldSystemFont（字体大小：22）
textField.textAlignment=.left
textField.keyboardType=.default
textField.minimumFontSize=13
textField.adjustsFontSizeToFitWidth=true
textField.text=self.\u text.wrappedValue
textField.placeholder=self.placeholder
textField.delegate=context.coordinator
返回文本字段
}
func updateUIView（textField:UITextField，context:context）{
如果自我成为第一反应者{
DispatchQueue.main.async{
textField.becomeFirstResponder（）
self.becomeFirstResponder=false
}
}
}
func makeCoordinator（）->Coordinator{
协调员（家长：自我）
}
类协调器：NSObject，UITextFieldDelegate{
var父项：MyTextField
初始化（父项：MyTextField）{
self.parent=parent
}
func textField应该返回（textField:UITextField）->Bool{
textField.resignFirstResponder（）辞职
}
func textField（textField:UITextField，shouldChangeCharacters范围：NSRange，replacementString:string）->Bool{
让currentText=textField.text？？“”
guard let stringRange=范围（范围，in:currentText）else{
返回错误
}
让updateText=currentText.replacingCharacters（在：stringRange中，带：string）
返回updateText.count<20
}
}
}
结构TextFieldFirstResponder:视图{
@国家私有变量becomeFirstResponder=false
@国家私有var text=“LLL”
私有变量占位符=“无标题”
var body：一些观点{
VStack{
ZStack（对齐：。尾部）{
MyTextField（becomeFirstResponder:self.$becomeFirstResponder，text:self.$text，占位符：self.placeholder）
.框架（宽度：343，高度：56，对齐：。前导）
.填充（边集（顶部：27，前导：13，底部：0，尾随：0））
.背景(
圆角转角（拐角半径：10，样式：连续）
.fill（颜色（UIColor.secondary系统背景））
.框架（宽度：342，高度：56，对齐：。中心）
)
奥纳佩尔先生{
self.becomeFirstResponder=true
}
}
Text（\（self.$Text.wrappedValue）/您不需要在此处使用
$
直接读取属性

Text(self.text) // <------ Do not use $

Text（self.Text）//
let updateText = currentText.replacingCharacters(in: stringRange, with: string)
self.parent.text = updateText          // << here !!
return updateText.count < 20