如何在 SwiftUI Picker 选项下方添加节页脚文本？

Question

我正在编写一个在 SwiftUI 上的应用程序，我使用 Picker 显示一个选项列表供用户选择。

当有人点击选择器并看到选项时，我想添加一些页脚文本来解释列表中的选项。

这是我想要完成的示例屏幕截图，取自 iOS 设置应用程序：

如何使用 SwiftUI 实现这一目标？

我在主屏幕上为包含选取器的部分定义了一个页脚（“这里是设置的简短描述。”）并且工作正常，但类似的代码不会在屏幕上添加一个页脚来显示选择器选项。

这是我的示例代码：

import SwiftUI

class ViewModel: ObservableObject {

    enum Option: String, Identifiable, CaseIterable, CustomStringConvertible {
        case optionOne
        case optionTwo
        case optionThree

        var id: Option {
            self
        }

        var description: String {
            rawValue.prefix(1).uppercased() + rawValue.dropFirst()
        }
    }

    @Published var selectedOption: Option = .optionOne {
        didSet {
            print("new option selected: \(selectedOption.description)")
        }
    }
}

struct ContentView: View {

    @ObservedObject var viewModel = ViewModel()

    var body: some View {

        NavigationView {
            Form {
                Section(footer: Text("Here is a short description of the setting.")) {
                    Picker(selection: $viewModel.selectedOption,
                           label: Text("Choice")) {
                            Section(footer: Text("This is some additional text to help the user understand the options.")) {
                                ForEach(ViewModel.Option.allCases) { type in
                                    Text(type.description)
                                }
                            }
                    }
                }

            }.navigationBarTitle(Text("Main Screen"))
        }
    }
}

此外，当这个列表加载时，我看到了一个奇怪的跳跃。我怎样才能避免这种情况？

Answer 1

你可能不需要另一个双页脚，也许只是一个提示标题

struct ContentView: View {

    @ObservedObject var viewModel = ViewModel()

    var body: some View {

        NavigationView {
            Form {
                Section(footer: Text("Here is a short description of the setting.")) {
                    Picker(selection: $viewModel.selectedOption,
                           label: Text("Choice")) {

                            ForEach(ViewModel.Option.allCases) { type in
                                Text(type.description)
                            }.navigationBarTitle("hint title here", displayMode: .inline)

                    }
                }.navigationBarTitle("Main Screen", displayMode: .inline)

            }.navigationBarTitle(Text("Main Screen"))
        }
    }
}

没有选择器，您可以构建自己的选项列表：

struct ContentView: View {

    @ObservedObject var viewModel = ViewModel()

    var body: some View {

        NavigationView {
            Form {
                Section(footer: Text("Here is a short description of the setting.")) {
                    NavigationLink(destination: SelectionItemView(selection: $viewModel.selectedOption)) {
                        Text("Choice")
                    }


                }.navigationBarTitle("Main Screen", displayMode: .inline)

            }.navigationBarTitle(Text("Main Screen"))
        }
    }
}


struct SelectionItemView: View {

    @Binding var selection: ViewModel.Option
    var body: some View{
        Form{
            Section(footer: Text("Here is a detailed description of the setting.")) {
                ForEach(0 ..< ViewModel.Option.allCases.count, id: \.self) { index in

                    HStack{
                        Button(action: {
                            self.selection  = ViewModel.Option.allCases[index]
                        }){Text(ViewModel.Option.allCases[index].description)}
                        Spacer()
                        if ( self.selection  ==  ViewModel.Option.allCases[index] ){
                            Image(systemName: "checkmark")
                        }
                    }

                }
            }}


    }
}