从 coredata SwiftUI 中删除多行

Question

我正在尝试使用编辑模式下的选择同时删除多个核心数据。但是，该行没有被删除。我不确定是什么问题。

我尝试在 ForEach(notes) 上添加 id:\.id 或 id:\.self

我的代码有什么问题？有没有其他方法可以删除多行？

struct TempNoteView: View {
    @Environment(\.managedObjectContext) private var viewContext

    @FetchRequest(sortDescriptors: [],animation: .default)
    private var notes: FetchedResults<Note>
    
    @State var editMode: EditMode = .inactive
    @State var selection = Set<UUID>()

    var body: some View {
        List(selection: $selection) {
            ForEach(notes) { note in
                    NavigationLink(destination: NoteView(note: note)) {
                        Text(note.name ?? "Untitled")
                        Spacer()

                        Button(action: {
                            if note.pin == false {
                                note.pin = true
                                saveContext()
                            } else {
                                note.pin = false
                                saveContext()
                            }
                        }) {
                            if note.pin {
                                Image("pinned").resizable().frame(width: 23, height: 23, alignment: .center)
                                .padding(.trailing, 10)
                            } else {
                                Image("not-pinned").resizable().frame(width: 23, height: 23, alignment: .center)
                                .padding(.trailing, 10)
                            }
                        }.buttonStyle(PlainButtonStyle())
                        
                    }
                    .padding()
                    .listRowInsets(EdgeInsets())
//                    .listRowBackground(Color.gray.opacity(0.1))
                    .background(Color.yellow.opacity(0.3))
                    .clipShape(RoundedRectangle(cornerRadius: 10))
                    .listStyle(SidebarListStyle())
                    .padding(.init(top: 10, leading: 0, bottom: 10, trailing: 0))
                    
                }.onDelete(perform: deleteNotes)
            }
            .environment(\.editMode, self.$editMode)
            .navigationTitle("Notes")
            .navigationBarItems(
                leading:
                    HStack {
                        editButton
                        deleteButton
                    },
                trailing: Button(action: {addNote()}, label: {
                Text("Add Note")
                Image("plus")
            })).onAppear(){
                UITableViewCell.appearance().selectionStyle = .none
            }
            
    }
    private var editButton: some View {
        if editMode == .inactive {
            return Button(action: {
                self.editMode = .active
                self.selection = Set<UUID>()
            }) {
                Text("Edit")
            }
        }
        else {
            return Button(action: {
                self.editMode = .inactive
                self.selection = Set<UUID>()
            }) {
                Text("Done")
            }
        }
    }
    
    private var deleteButton: some View {
        if editMode == .inactive {
            return Button(action: {}) {
                Image("")
            }
        } else {
            return Button(action: deleteAllNotes) {
                Image(systemName: "trash")
            }
        }
    }
    
    private func deleteAllNotes() {
        for id in selection {
            if let index = notes.lastIndex(where:{ $0.id == id }) {
                viewContext.delete(notes[index])
            }
        }
        selection = Set<UUID>()
    }
    
    
    func saveContext() {
        do {
            try viewContext.save()
        } catch {
            let error = error as NSError
            fatalError("Unresolved Error: \(error)")
        }
    }
    
    private func deleteNotes(offsets: IndexSet) {
        withAnimation {
            offsets.map { notes[$0] }.forEach(viewContext.delete)
            saveContext()
        }
    }
    
    private func addNote() {
        withAnimation {
            let newNote = Note(context: viewContext)
            newNote.id = UUID()
            newNote.name = "New Note"
            newNote.createdAt = Date()
            newNote.pin = false
            saveContext()
            
        }
    }
}

Answer 1

将您的 ForEach 更改为

ForEach(notes, id:\.self) { note in

然后将 Set 更改为将 Notes 作为类型

@State var selection = Set<Notes>()

然后在您的 deleteAllNotes（我将其重命名为 deleteAllSelectedNotes）中删除每个选定的笔记。

private func deleteAllNotes() {
    for item in selection {
        viewContext.delete(item)
    }
    selection = Set<Note>()
}