Question

struct ACFTHhistory：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")) {

这是我放置@State属性以触发我的有条件的，有效的地方，但是它有问题。

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

func delete(at offsets: IndexSet) {

    self.showingDeleteAlert = true

我试图通过另一个@State属性设置条件。我能够删除该记录，但它会引发错误并且出现故障。

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

        } catch {
            print(error)
        }
    }
}

Answer 1

您可能会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
            }

删除CoreData记录之前在带有Alert的ForEach上使用.onDelete

1 个答案: