SwiftUI中子视图如何设置私有状态变量？跨视图传值报错解决方案

• 核心报错来自第二个视图kek的属性未正确初始化：你声明了@State var Question : String但没有给初始值，也没有自定义构造方法接收该参数，Swift自动生成的构造器要求必须传入所有未初始化的属性，你当前调用kek(One: multiplicationTable, Two: amountQuestions)时缺少Question参数，所谓的「无法传递私有变量」是构造器不匹配产生的衍生错误提示。
• 补充说明：ContentView里的@State private变量只是限制当前视图内部访问修改，将其值作为普通参数传递给下一个视图的存储属性是完全合法的，不会引发传值错误。

1. 给kek视图中未初始化的@State属性添加默认值，同时在视图加载时调用nextQuestion生成第一道题目，同时调整命名符合Swift开发规范：

import SwiftUI

// 类型名首字母大写
struct Kek: View {
    // 属性名首字母小写，语义清晰
    let selectedTable: Int
    let questionCount: Int
    
    // 给状态属性设置默认值
    @State private var currentQuestion = ""
    @State private var answer = ""
    @State private var factor1 = 0
    @State private var factor2 = 0
    
    func nextQuestion(){
        factor1 = selectedTable
        factor2 = Int.random(in: 0...10)
        currentQuestion = "\(factor1) * \(factor2)"
    }
    
    var body: some View {
        VStack {
            Text("Question: What is \(currentQuestion)?")
            Form {
                Section {
                    TextField("Enter answer", text: $answer)
                        .keyboardType(.decimalPad)
                }
            }
          
            Button ("Next") {
                nextQuestion()
                answer = ""
            }
            .padding(50)
            .background(Color.red)
            .foregroundColor(.white)
            .clipShape(Circle())
        }
        // 视图加载时自动生成第一道题
        .onAppear {
            nextQuestion()
        }
    }
}

struct Kek_Previews: PreviewProvider {
    static var previews: some View {
        Kek(selectedTable: 1, questionCount: 2)
    }
}

2. 修改ContentView中的冗余代码，移除NavigationLink中嵌套的多余Button，修正数组命名笔误：

import SwiftUI

struct ContentView: View {
    @State private var multiplicationTable = 1
    @State private var amountQuestions = 1
    
    let multiplicationTables = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    // 修正原命名多打s的笔误
    let amountQuestionsArray = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
    
    var body: some View {
        // iOS16+推荐用NavigationStack替代已废弃的NavigationView
        NavigationStack {
            VStack {
                Picker(selection: $multiplicationTable, label: Text("Choose multiplication table")) {
                    // 直接遍历数组元素避免索引越界风险
                    ForEach(multiplicationTables, id: \.self) { table in
                        Text("\(table)")
                    }
                }
                .padding(.vertical, 32)
                
                Text("Choose number of Questions")
                Picker("Select number of questions", selection: $amountQuestions) {
                    ForEach(amountQuestionsArray, id: \.self) { count in
                        Text("\(count)")
                    }
                }
                
                // 移除多余的Button嵌套，NavigationLink本身支持点击交互
                NavigationLink(destination: Kek(selectedTable: multiplicationTable, questionCount: amountQuestions)
                    .navigationBarHidden(true)) {
                    Text("GO")
                        .padding(50)
                        .background(Color.red)
                        .foregroundColor(.white)
                        .clipShape(Circle())
                }
                .navigationTitle("Choose Multiplication Table")
                .navigationBarTitleDisplayMode(.inline)
            }
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

内容的提问来源于stack exchange，提问作者Charlie Tan