SwiftUI错误代码，我不知道如何解决

Question

struct QuizView: View {
    // The question pool.
    var questions = [("What is the capital of France?", ["Paris", "London", "New York", "San Francisco"], "Paris"),
                     ("What is the capital of Italy?", ["Rome", "Paris", "Madrid", "Berlin"], "Rome"),
                     ("What is the capital of Spain?", ["Barcelona", "Madrid", "Rome", "Paris"], "Madrid"),
                     ("What is the capital of Germany?", ["Berlin", "Paris", "London", "New York"], "Berlin"),
                     ("What is the capital of the UK?", ["London", "Paris", "Madrid", "New York"], "London"),
    ]

    // The current question.
    @State var currentQuestion = 0

    // The user's score.
    @State var score1 = 0

    // The indices of the remaining questions.
    @State var remainingQuestions = [Int]()
    
    var body: some View {
        VStack {
            currentView
        }.onAppear {
            questions.shuffle() // shuffle the questions array
            remainingQuestions = Array(0..<questions.count) // recreate remainingQuestions array
        }
    }
}

错误信息：

不能对不可变值使用可变成员：'self' 是不可变的

我实际上想编写代码，以便问题会随机播放，但显然这发生了，我也是新手。

Answer 1

如果你想在 SwiftUI 视图中操作一个 var，你需要将它包装到一个 @State 属性包装器中。例如。：

@State var questions = [("What is the capital of France?", ["Paris", "London", "New York", "San Francisco"], "Paris"),
                     ("What is the capital of Italy?", ["Rome", "Paris", "Madrid", "Berlin"], "Rome"),
                     ("What is the capital of Spain?", ["Barcelona", "Madrid", "Rome", "Paris"], "Madrid"),
                     ("What is the capital of Germany?", ["Berlin", "Paris", "London", "New York"], "Berlin"),
                     ("What is the capital of the UK?", ["London", "Paris", "Madrid", "New York"], "London"),
    ]