Xcode SwiftUI中的绑定在循环内无法工作

根据我的理解，我编写了以下代码，用于展开/折叠列表中的一个部分

struct WORKING_CollapsableListView: View {
  @State var sectionExpansionStates = [true, true, true]

  var body: some View {
    VStack {
      List {
          Section(header: CollapsableSectionHeader(expansionState: self.$sectionExpansionStates[0])) {
            if self.sectionExpansionStates[0] {
              ForEach(0..<10) { item in
                Text("\(item) is \(self.sectionExpansionStates[0] ? "Expanded" : "Collapsed")")
                  .frame(height: self.sectionExpansionStates[0] ? 10 : 10)
              }
            }
          }

        Section(header: CollapsableSectionHeader(expansionState: self.$sectionExpansionStates[1])) {
          if self.sectionExpansionStates[1] {
            ForEach(0..<10) { item in
              Text("\(item) is \(self.sectionExpansionStates[1] ? "Expanded" : "Collapsed")")
                .frame(height: self.sectionExpansionStates[1] ? 10 : 10)
            }
          }
        }
        Section(header: CollapsableSectionHeader(expansionState: self.$sectionExpansionStates[2])) {
          if self.sectionExpansionStates[2] {
            ForEach(0..<10) { item in
              Text("\(item) is \(self.sectionExpansionStates[2] ? "Expanded" : "Collapsed")")
                .frame(height: self.sectionExpansionStates[2] ? 10 : 10)
            }
          }
        }
      }
    }
  }
}

struct CollapsableSectionHeader: View {
  @Binding var expansionState: Bool

  var body: some View {
    Button(action: {
      self.expansionState.toggle()
    }) {
      Text("HEADER: \(expansionState ? "Expanded" : "Collapsed")")
        .bold()
    }
  }
}

---

这是由于每个对象的静态范围。。。正如我在这里所经历的，这是SwiftUI中最混乱的概念。。无论如何-解决方案是为节使用显式模型的动态容器

这里是代码的简化工作演示（但是这个想法应该很容易被未提供的组件采用）

使用Xcode 11.4/iOS 13.4进行测试

//节的简单演示模型
结构截面模型：可识别{
让id:Int
var=true
}
结构TestCollapsableListView:视图{
//具有模型的动态容器，状态已触发
@State var sections=[SectionModel（id:0）、SectionModel（id:1）、SectionModel（id:2）]
var body：一些观点{
VStack{
名单{
ForEach（sections）{section in
节（标题：按钮（“节\（节.id）”）{self.sections[Section.id].expanded.toggle（）}）{
如果第.1节已展开{
ForEach（0..谢谢！哇。这真是难以置信。在我的实际代码中，我使用的是类似的状态模型，但我现在看到的唯一区别是，我使用的是ForEach中的索引，而不是
部分。id
，这很有效！这太微妙了，我自己无法理解。
struct NOT_WORKING_CollapsableListView: View {
  @State var sectionExpansionStates = [true, true, true]

  var body: some View {
    VStack {
      List {
        ForEach(0 ..< 3) { section in
          Section(header: CollapsableSectionHeader(expansionState: self.$sectionExpansionStates[section])) {
            if self.sectionExpansionStates[section] {
              ForEach(0..<10) { item in
                Text("\(item) is \(self.sectionExpansionStates[section] ? "Expanded" : "Collapsed")")
                  .frame(height: self.sectionExpansionStates[section] ? 10 : 10)
              }
            }
          }
        }
      }
    }
  }
}

// simple demo model for sections
struct SectionModel: Identifiable {
    let id: Int
    var expanded = true
}

struct TestCollapsableListView: View {
  // dynamic container with model, state is triggered
  @State var sections = [SectionModel(id: 0), SectionModel(id: 1), SectionModel(id: 2)]

  var body: some View {
    VStack {
      List {
        ForEach(sections) { section in
          Section(header: Button("Section \(section.id)") { self.sections[section.id].expanded.toggle() }) {
            if section.expanded {
              ForEach(0..<10) { item in
                Text("\(item) is \(section.expanded ? "Expanded" : "Collapsed")")
                  .frame(height: section.expanded ? 10 : 10)
              }
            }
          }
        }
      }
    }
  }
}