Question

我无法发布用于删除和移动SwiftUI列表中带有部分的行的方法。

我有用于类别的模型：

struct Category: Identifiable {

    var id = UUID()
    var title: String
    var number: Int
    var items: [ChecklistItem]

    func deleteListItem(whichElement: IndexSet) {
      items.remove(atOffsets: whichElement)
    }

    func moveListItem(whichElement: IndexSet, destination: Int) {
      items.move(fromOffsets: whichElement, toOffset: destination)
    }


}

ChecklistItem：

struct ChecklistItem: Identifiable {
  
  let id = UUID()
  var name: String
  var isChecked = false
    
}

和清单：

class Checklist: ObservableObject {

  @Published var items = [Category]()
}

这是我的列表视图：

struct ChecklistView: View {

  @EnvironmentObject var checklist: Checklist
  @State var newChecklistItemViewIsVisible = false

  var body: some View {
    NavigationView {
      List {
        ForEach(checklist.items) { category in
            Section(header: Text(category.title)) {
                ForEach(category.items) { item in
                    HStack {
                      Text(item.name)
                      Spacer()
                      Text(item.isChecked ? "✅" : "?")
                    }
                    .background(Color.white)
                    .onTapGesture {
                        if let matchingIndex =
                            checklist.items[category.number].items.firstIndex(where: { $0.id == item.id }) {
                            checklist.items[category.number].items[matchingIndex].isChecked.toggle()
                      }
                    }
                }
                .onDelete(perform: checklist.items[category.number].deleteListItem)
                .onMove(perform: checklist.items[category.number].moveListItem)
            }
        }
      }
      .navigationBarItems(
        leading: Button(action: {
            self.newChecklistItemViewIsVisible = true

        }) {
          HStack {
            Image(systemName: "plus.circle.fill")
            Text("Add")
          }
        },
        trailing: EditButton()
      )
      .navigationBarTitle("List")
    }
    .onAppear {
        //print("ContentView appeared!")
    }
    .sheet(isPresented: $newChecklistItemViewIsVisible) {
      NewChecklistItemView(checklist: self.checklist)
    }
  }
}

struct ContentView_Previews: PreviewProvider {
  static var previews: some View {
      ChecklistView()

  }
}

我无法使用.ondelete和.onmove方法，因为无法在struct中使用变异方法。如何更改我的代码以添加用于删除和移动带有节的列表中的项目的功能？

Answer 1

您需要为函数使用mutating修饰符，并更新代码

struct Category: Identifiable {

    // ... other code

    mutating func deleteListItem(_ whichElement: IndexSet) {
      items.remove(atOffsets: whichElement)
    }

    mutating func moveListItem(_ whichElement: IndexSet, _ destination: Int) {
      items.move(fromOffsets: whichElement, toOffset: destination)
    }
}

和用法类似

.onDelete { indexSet in 
   checklist.items[category.number].deleteListItem(indexSet) 
}
.onMove { indexSet, dest in 
   checklist.items[category.number].moveListItem(indexSet, dest) 
}

.ondelete具有部分的SwiftUI列表

1 个答案: