串列中的TextField在SwiftUI中無法正常作業

此問題與 iPhone 12 應用程式的 SwiftUI 相關，使用 xcode 13.1。我在每一行中構建了一個帶有 TextField 的串列，但是每次我嘗試編輯內容時，只允許我點擊一次并只輸入一個字符，然后不能再繼續輸入字符，除非我再次點擊然后輸入另一個字符.我是不是寫錯了什么代碼？

    class PieChartViewModel: ObservableObject, Identifiable {
@Published var options = ["How are you", "你好", "Let's go to zoo", "OKKKKK", "什麼情況？？", "yesssss", "二百五", "明天見"]
}

struct OptionsView: View {
    @ObservedObject var viewModel: PieChartViewModel
    
    var body: some View {
        NavigationView {
            List {
                ForEach($viewModel.options, id: \.self) { $option in
                    TextField(option, text: $option)
                }
            }
            .navigationTitle("Options")
            .toolbar {
                ToolbarItem(placement: .bottomBar) {
                    Button {
                        addNewOption()
                    } label: {
                        HStack {
                            Image(systemName: "plus")
                            Text("Create a new option")
                        }
                    }
                }
            }
        }
    }
    
    func addNewOption() {
        viewModel.options.insert("", at: viewModel.options.count)
    }
}

struct OptionsView_Previews: PreviewProvider {
    static var previews: some View {
        let pieChart = PieChartViewModel()
        OptionsView(viewModel: pieChart)
    }
}

uj5u.com熱心網友回復：

歡迎使用 StackOverflow！你的問題是，你是直接的更新ObservableObject中TextField。您對模型所做的每一次更改都會導致您的視圖重繪，當然，這會將您的注意力從TextField. 最簡單的答案是Binding在TextField. 這將導致模型更新，而無需不斷重繪您的視圖：

struct OptionsView: View {
    // You should be using @StateObject instead of @ObservedObject, but either should work.
    @StateObject var model = PieChartViewModel()
    @State var newText = ""
    var body: some View {
        NavigationView {
            VStack {
                List {
                    ForEach(model.options, id: \.self) { option in
                        Text(option)
                    }
                }
                
                List {
                    //Using Array(zip()) allows you to sort by the element, but use the index.
                    //This matters if you are rearranging or deleting the elements in a list.
                    ForEach(Array(zip(model.options, model.options.indices)), id: \.0) { option, index in
                        // Binding implemented here.
                        TextField(option, text: Binding<String>(
                            get: {
                                model.options[index]
                            },
                            set: { newValue in
                                //You can't update the model here because you will get the same behavior
                                //that you were getting in the first place.
                                newText = newValue
                            }))
                            .onSubmit {
                                //The model is updated here.
                                model.options[index] = newText
                                newText = ""
                            }
                    }
                }
                .navigationTitle("Options")
                .toolbar {
                    ToolbarItem(placement: .bottomBar) {
                        Button {
                            addNewOption()
                        } label: {
                            HStack {
                                Image(systemName: "plus")
                                Text("Create a new option")
                            }
                        }
                    }
                }
            }
        }
    }
    
    func addNewOption() {
        model.options.insert("", at: model.options.count)
    }
}

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