Update UITextField.text不更新绑定值

Question

我有多个TextField，允许用户从键盘输入数字，并从[+/-]按钮输入减号。问题是，当我更新[editingTextField.text]的值时，Textfield中显示的值被更新，但绑定值[text]没有更新。我的[+/-]按钮如何更新当前编辑的TextField？

谢谢你的帮助！

import SwiftUI
struct TestView: View {

@State private var showTextFieldToolbar = false
@State private var text = ""
@State private var text2 = ""
@State private var currentText = ""
@State var editingTextField: UITextField? = nil
var body: some View {
ZStack {
VStack {
Text(currentText)
TextField("Watts", text: $text
, onEditingChanged: { editingChanged in
}
, onCommit: {
showTextFieldToolbar = false
})
.keyboardType(.decimalPad)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()

TextField("Von", text: $text2) { isChanged in
} onCommit: {
showTextFieldToolbar = false
}
.keyboardType(.decimalPad)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
}
.onReceive(NotificationCenter.default.publisher(for: UITextField.textDidBeginEditingNotification)) { obj in
self.editingTextField = obj.object as? UITextField
showTextFieldToolbar = true
}
.onChange(of: text, perform: { value in
currentText = text
})
.onChange(of: text2, perform: { value in
currentText = text2
})
VStack {
Spacer()
if showTextFieldToolbar {
HStack {
Button("+/-") {
plusMinusAction()
}
.foregroundColor(Color.black)
.padding(.trailing, 12)
Spacer()
Button("OK") {
showTextFieldToolbar = false
editingTextField?.resignFirstResponder()
}
.foregroundColor(Color.black)
.padding(.trailing, 12)
}
.frame(idealWidth: .infinity, maxWidth: .infinity,
idealHeight: 44, maxHeight: 44,
alignment: .center)
.background(Color.gray)
}
}
}
}
func plusMinusAction() {
if let text = editingTextField?.text {
if text.hasPrefix("-") {
editingTextField?.text = String(text.suffix(text.count - 1))
} else {
editingTextField?.text = "-(text)"
}
}
}
}
struct TestView_Previews: PreviewProvider {
static var previews: some View {
TestView()
}
}

EDIT：我在onEditingChanged事件中更新了绑定值，它运行得很好。

onEditingChanged: { isChanged in
if !isChanged {
text = editingTextField?.text ?? text
editingTextField = nil
}
}

Answer 1

编辑：

这是我用来使它工作的代码。也就是说，当点击[+/-]按钮时，text1和text2的值会更新。(暂时忽略currentText(

import SwiftUI

@main
struct TestApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
struct ContentView: View {
var body: some View {
TestView()
}
}
class TextModel: ObservableObject {
@Published var flag = false  // true="-", false=""
@Published var text1 = ""
@Published var text2 = ""

func toggleUpdate() {
flag.toggle()
update()
}

func update() {
if flag {
text1 = text1.hasPrefix("-") ? text1 : "-" + text1
text2 = text2.hasPrefix("-") ? text2 : "-" + text2
} else {
text1 = text1.hasPrefix("-") ? String(text1.dropFirst()) : text1
text2 = text2.hasPrefix("-") ? String(text2.dropFirst()) : text2
}
}
}
struct TestView: View {

@StateObject var textModel = TextModel()

@State private var showTextFieldToolbar = false
@State private var currentText = ""
@State var editingTextField: UITextField? = nil

var body: some View {
ZStack {
VStack {
Text(currentText)
TextField("Watts", text: $textModel.text1, onCommit: {
showTextFieldToolbar = false
currentText = textModel.text1
})
.onTapGesture {
showTextFieldToolbar = true
currentText = textModel.text1
textModel.update()
}
.keyboardType(.decimalPad)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()

TextField("Von", text: $textModel.text2, onCommit: {
showTextFieldToolbar = false
currentText = textModel.text2
})
.onTapGesture {
showTextFieldToolbar = true
currentText = textModel.text2
textModel.update()
}
.keyboardType(.decimalPad)
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding()
}
.onReceive(NotificationCenter.default.publisher(for: UITextField.textDidBeginEditingNotification)) { obj in
self.editingTextField = obj.object as? UITextField
showTextFieldToolbar = true
}

VStack {
Spacer()
if showTextFieldToolbar {
HStack {
Button("+/-") {
plusMinusAction()
}
.foregroundColor(Color.black)
.padding(.trailing, 12)
Spacer()
Button("OK") {
textModel.update()
if let txt = editingTextField?.text {
currentText = txt
}
showTextFieldToolbar = false
editingTextField?.resignFirstResponder()
}
.foregroundColor(Color.black)
.padding(.trailing, 12)
}
.frame(idealWidth: .infinity, maxWidth: .infinity,
idealHeight: 44, maxHeight: 44,
alignment: .center)
.background(Color.gray)
}
}
}
}

func plusMinusAction() {
if let txt = editingTextField?.text {
if txt.hasPrefix("-") {
editingTextField?.text = String(txt.dropFirst())
} else {
editingTextField?.text = "-(txt)"
}
}
if let txt = editingTextField?.text {
currentText = txt
}
textModel.toggleUpdate()
}

}