从coredata SwiftUI中删除多行

Question

我试图在编辑模式下使用选择同时删除多个核心数据。但是，该行不会被删除。我不确定问题出在哪里。

我所尝试的是在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>()
}