ios - 如何在 SwiftUI Picker 选项下方添加节页脚文本？

Question

我正在 SwiftUI 上编写一个应用程序，我使用 Picker 来呈现一个选项列表供用户选择。

我想添加一些页脚文本来解释当有人点击选择器并看到选项时列表中的选项。

这是我想要完成的示例屏幕截图，取自 iOS 设置应用程序:

我如何使用 SwiftUI 实现这一目标？

我在主屏幕上为包含选择器的部分定义了一个页脚(“这是设置的简短描述。”)并且工作正常，但类似的代码不会在显示的屏幕上添加页脚选择器选项。

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，当加载此列表时，我看到一个奇怪的跳跃。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")
                        }
                    }

                }
            }}


    }
}