SwiftUI-更新@State不会更改视图

我对SwiftUI有点陌生，我想创建一个带有“快速开发人员访问”按钮（又名“User1”）的登录屏幕，它应该填充用户和密码字段

当我点击“User1”按钮时，

LoginScreen

的

@State

电话和密码变量正确地填充了正确的值，但是

CustomLoginField

没有显示更新的值

我还尝试使用

@Binding var phone:String

代替

@State

，但结果相同

我知道

@State

应该是私有的。。因此，我也想知道编写代码的正确方法

import SwiftUI

struct LoginScreen: View {
    
    private let developers:[User] = [
        .init(name: "User1", phone: "12345678", password: "1234")]
    
    private let minSpaceFromBottom:CGFloat = 30
    @State fileprivate var phone:String = ""
    @State fileprivate var password:String = ""
    
    var body: some View {
        GeometryReader { geo in
            ZStack {
                Color(#colorLiteral(red: 0.9965313077, green: 0.9966740012, blue: 0.9965001941, alpha: 1))
                VStack(alignment: .center) {
                    Spacer().frame(height: geo.safeAreaInsets.top)
                        
                    CustomLoginField(inputStr:phone, keyboard: .numberPad, placeholder:"PHONE", formatedPhoneNumber:true, maxLength: 10)
                    CustomLoginField(inputStr:password, keyboard: .numberPad, placeholder: "PASSWORD", isSecure: true, maxLength: 4)
                       
                            HStack {
                                ForEach(developers, id:\.id) { developer in
                                    Text(developer.name!)
                                        .frame(width: 70, height: 35, alignment: .center)
                                        .onTapGesture {
                                            phone = developer.phone
                                            password = developer.password
                                        }
                                }
                        }
                        
                        Spacer()
                        
                    }
                    .frame(width: geo.size.width * 0.9, alignment: .leading)
                    Spacer()
                        .frame(height: minSpaceFromBottom)
                }
            }
    }
}

private struct CustomLoginField: View {
    
    @State var inputStr:String
    var keyboard:UIKeyboardType = .default
    var placeholder:String
    var isSecure:Bool = false
    var formatedPhoneNumber = false
    var maxLength = 0
    var underlineColor:UIColor {
        let underlineOnColor = UIColor(.blue)
        let underlineOffColor:UIColor = .lightGray
        return inputStr.count >= maxLength ? underlineOnColor : underlineOffColor
    }
    
    var body: some View {
        
        VStack(alignment:.leading, spacing:-8) {
            Text(placeholder)
                .opacity(!inputStr.isEmpty ? 1 : 0)
                .animation(Animation.easeIn(duration: !inputStr.isEmpty ? 0.3 : 0))
            
            if isSecure {
                SecureField(placeholder, text: $inputStr)
                    .modifier(CustomTextFieldModifire(parent: self))
            } else {
                TextField(placeholder, text: $inputStr)
                    .modifier(CustomTextFieldModifire(parent: self))
            }
            
            Color(underlineColor)
                .frame(width: UIScreen.main.bounds.width * 0.88, height: 1)
                .animation(Animation.easeIn(duration:0.3))
        }
    }
}

private struct CustomTextFieldModifire: ViewModifier {
    var parent:CustomLoginField
    
    func body(content: Content) -> some View {
        content
            .frame(height: 45)
            .keyboardType(parent.keyboard)
            .onReceive(parent.inputStr.publisher.collect()) {
                var result = String($0)
                
                if parent.maxLength > 0 && result.count > parent.maxLength {
                    result = String(result.prefix(parent.maxLength))
                }
                
                parent.inputStr = result
            }
    }
}

private struct User:Identifiable {
    let id = UUID()
    var name:String?
    var phone:String
    var password:String
}

struct LoginScreen_Previews: PreviewProvider {
    static var previews: some View {
        LoginScreen()
            .previewDevice("iPhone 8")
    }
}

---

你只是犯了个小错误

在customloginField中，需要将inputStr:String定义为绑定变量

@Binding var inputStr:String

在使用时，您必须按照以下方式使用它

CustomLoginField(inputStr:self.$phone, keyboard: .numberPad, placeholder:"PHONE", formatedPhoneNumber:true, maxLength: 10)
CustomLoginField(inputStr:self.$password, keyboard: .numberPad, placeholder: "PASSWORD", isSecure: true, maxLength: 4)

注意到电话和密码前的“$”吗

检查下面的SO线程，了解@state与@binding的关系