Question

我想要一个自定义按钮结构，该结构接收一个视图作为参数，单击该按钮时将显示为模式。但是，view参数始终为空，并且找不到我正在执行的错误。我的按钮结构如下所示：

struct InfoButton<Content:View>: View {
    @State private var showingInfoPage: Bool
    private var infoPage: Content
    init(infoPage: Content, showingInfoPage: Bool) {
        self.infoPage = infoPage
        _showingInfoPage = State(initialValue: showingInfoPage)
    }
    var body: some View {
      return
        Button(action: {
               self.showingInfoPage.toggle()
        }) {
            Image(systemName: "info.circle")
                .resizable()
                .frame(width: 25, height: 25)
                .foregroundColor(.white)
                .padding()
         }.sheet(isPresented: self.$showingInfoPage) {
            self.infoPage
        }.frame(minWidth: 0, maxWidth: .infinity, alignment: .topTrailing)
    }
}

此按钮位于我正在为其他多个视图创建的模板的导航栏中。我认为该模板最相关的部分是：

protocol TrainingView {
    var title: String { get }
    var subheadline: String { get }
    var asAnyView: AnyView { get }
    var hasInfoPage: Bool { get }
    var infoPage: AnyView { get }
}

extension TrainingView where Self: View {
    var asAnyView: AnyView {
        AnyView(self)
    }
    var hasInfoPage: Bool {
        false
    }
    var infoPage: AnyView {
        AnyView(EmptyView())
    }
}
struct TrainingViewTemplate: View {
    @State var showInfoPage: Bool = false
    @State var viewIndex: Int = 0
    var body: some View {
//the views that conform to the template
        let views: [TrainingView] = [
            ExerciseView(),
            TrainingSessionSummaryView()
        ]
        return NavigationView {
                ViewIterator(views, self.$viewIndex) { exerciseView in
                    VStack {
                        VStack {
                            Text(exerciseView.title)
                                .font(.title)
                                .fontWeight(.semibold).zIndex(1)
                            Text(exerciseView.subheadline)
                                .font(.subheadline)
                            Spacer()
                            exerciseView.asAnyView.frame(maxWidth: .infinity, maxHeight: .infinity)
                        }
                    }.navigationBarItems(trailing: (exerciseView.hasInfoPage == true ?  InfoButton(infoPage: exerciseView.infoPage, showingInfoPage: self.showInfoPage) : nil))
                    
                }
            }
}

我调试到了要初始化NavigationBarItems的地步。此时，练习视图具有“ hasInfoPage”和“ infoPage”本身的内容。

一个示例性的“锻炼视图”具有这样的标题：

struct ExerciseView: View, TrainingView {
    var title: String = "Strength Session"
    var subheadline: String = "Pushups"
    var numberOfExercise: Int = 1
    @State var ratingValue: Double = 0
    @Environment(\.presentationMode) var presentationMode
    var hasInfoPage: Bool = true
    var infoPage = ExerciseDetailView()

因此，在此视图中，infoPage用我在TemplateView中收到的ExercieDetailView（）进行了初始化，但是，一旦单击InfoButton，调试器将显示一个空的infoPage，即使“ showingInfoPage”变量包含正确的值。

Answer 1

您未确认协议，因此显示了infoPage中的默认extension TrainingView。

解决方案是

struct ExerciseView: View, TrainingView {
    // .. other code here

    var infoPage = AnyView(ExerciseDetailView()) // << here !!

``

将视图作为参数传递给Button，将其触发为模态

1 个答案: