Swift测验应用：QuestionView无法切换至下一题的问题

问题根源 #

1. 数据未被观察：Quiz类是引用类型，但未遵循ObservableObject协议，修改progress和score时无法触发View刷新，导致界面感知不到进度变化。
2. 题目参数未动态绑定：QuestionView通过初始化参数接收固定的question，没有和quiz.progress关联，即使进度更新，题目也不会自动切换。
3. 状态更新无响应：点击答案修改quiz.progress后，因View未监听Quiz实例的变化，界面无法同步更新内容。

修复步骤 #

1. 修改Quiz模型，使其支持状态监听

让Quiz遵循ObservableObject，并将需要监听的属性标记为@Published：

import Combine

class Quiz: Identifiable, ObservableObject {
    let id = UUID()
    let name: String
    let illustration: String
    let difficulty: Difficulty
    let questions: [Question]
    
    @Published var score: Int
    @Published var progress: Int

    init(name: String, illustration: String, difficulty: Difficulty, questions: [Question], score: Int, progress: Int) {
        self.name = name
        self.illustration = illustration
        self.difficulty = difficulty
        self.questions = questions
        self.score = score
        self.progress = progress
    }
}

2. 重构QuestionView，动态绑定当前题目

移除固定的question参数，改为从quiz中动态获取当前题目，并通过@ObservedObject监听quiz的变化：

struct QuestionView: View {
    @ObservedObject var quiz: Quiz
    @State private var isFinished = false
    @State private var success = true
    
    // 动态计算当前题目
    private var currentQuestion: Question {
        quiz.questions[quiz.progress]
    }

    var body: some View {
        VStack(spacing: 40) {
            VStack {
                Text(quiz.name)
                    .font(.title3)
                    .bold()
                
                HStack(spacing: 20) {
                    ProgressBar(progress: 250 / CGFloat(quiz.questions.count) * CGFloat(quiz.progress))
                    Text("\(quiz.progress + 1)/\(quiz.questions.count)")
                        .bold()
                }
            }
            
            Text(currentQuestion.questionText)
                .font(.title)
                .fontWeight(.semibold)
                .frame(width: 300)
            
            Spacer()
            
            LazyVGrid(columns: [GridItem(.adaptive(minimum: 160, maximum: 240))], spacing: 10) {
                ForEach(currentQuestion.answers) { answer in
                    AnswerRow(answer: answer)
                        .onTapGesture {
                            if answer.isCorrect {
                                if success {
                                    quiz.score += 1
                                }
                                quiz.progress += 1
                                isFinished = true
                            } else {
                                success = false
                            }
                        }
                }
            }
            
            NavigationLink {
                // 检测是否完成所有题目，完成则跳转结果页
                if quiz.progress < quiz.questions.count {
                    QuestionView(quiz: quiz)
                } else {
                    Text("测验完成！得分：\(quiz.score)")
                    // 替换为你的结果页面，比如 ResultView(quiz: quiz)
                }
            } label: {
                PrimaryButton(text: "Continuer")
            }
            .disabled(!isFinished) // 启用禁用逻辑，防止未答题跳转

        }
        .padding(.vertical, 60)
        .navigationBarHidden(true)
    }
}

额外优化 #

• 简化了答案点击的逻辑判断，代码更简洁；
• 修正了ForEach中变量名的语义错误（从index改为answer）；
• 增加测验完成的判断，避免超出题目数组索引；
• 启用NavigationLink的禁用状态，提升交互合理性。

内容的提问来源于stack exchange，提问作者Julien01