在删除 CoreData 记录之前，在 ForEach 上使用 Alert .onDelete

Question

构造 ACFTHistory：查看 { @Environment(.managedObjectContext) var moc @FetchRequest(entity: ACFTScores.entity(), sortDescriptors: [NSSortDescriptor(keyPath: \ACFTScores.createdAt, ascending: false)]) var acftScores: FetchedResults

@State var isPresented = false
@State private var showingDeleteAlert = false

var body: some View {
    NavigationView {
        List {
            Section(header: Text("ACFT History")) {
                ForEach(acftScores, id: \.id) { score in
                    ACFTHistoryView(createdAt: "\(score.createdAt ?? Date())", totalScore: score.totalScore ?? "0")
                        .foregroundColor(.white)
                }.onDelete(perform: delete)
            }.alert(isPresented: $showingDeleteAlert) {
                Alert(title: Text("Delete Score"), message: Text("Delete Recore Permanently?"), primaryButton: .destructive(Text("Delete")) {

This is where I put the @State property to trigger my conditional, worked but it was buggy.

                    }, secondaryButton: .cancel())
            }
        }.navigationBarTitle(Text("ACFT Scoreboard"))
            .navigationBarItems(trailing: EditButton())
    }
}

func delete(at offsets: IndexSet) {

    self.showingDeleteAlert = true

I tried to put a conditional with another @State property. I was able to delete the record but it throws errors and is glitchy.

    for index in offsets {
        let score = acftScores[index]
        moc.delete(score)
        do {
            try self.moc.save()

        } catch {
            print(error)
        }
    }
}

Answer 1

您可以考虑添加一个额外的状态值：

                        @State var offsets: IndexSet?

            var body: some View {


                NavigationView {
                    List {


                        Section(header: Text("ACFT History")) {
                            ForEach(acftScores, id: \.id) { score in
                              ACFTHistoryView(createdAt: "\(score.createdAt ?? Date())", totalScore: score.totalScore ?? "0")
                    .foregroundColor(.white)
                            }.onDelete (perform: delete)
                        }
                        }
                    .navigationBarTitle(Text("ACFT Scoreboard"))
                    .navigationBarItems(trailing: EditButton()).alert(isPresented: self.$showingDeleteAlert){
                                       Alert(title: Text("Delete Score"), message: Text("Delete Recore Permanently?"), primaryButton: .destructive(Text("Delete")) {
                                        if let offsets = self.offsets{
                                        for index in offsets {
                                               let score = acftScores[index]
                                               moc.delete(score)
                                               do {
                                                   try self.moc.save()

                                               } catch {
                                                   print(error)
                                               }
                                           }
                                        }
                                        }, secondaryButton: .cancel())}
                }
                }

                 func delete(at offsets: IndexSet) {
                self.showingDeleteAlert = true
                    self.offsets = offsets
            }

在删除 CoreData 记录之前，在 ForEach 上使用 Alert .onDelete

.onDelete on ForEach with Alert before delete CoreData Record

alert

core-data

swiftui