iOS的一个巨大惊喜：核心数据控制器仅适用于基本领域。奇怪但真实。

Question

我正试图弄清楚我可能做错了什么（或者，当然是对关系，获取等所有东西的误解）。

在第一次搜索时，当我阅读该问题的标题时，希望该问题对我有帮助，但是我错了：

SwiftUI TabView with List not refreshing after objected deleted from / added to Core Data

反正...

在我的应用中，当我触摸客户项目时，详细视图及其数据会正确显示。如果我更改任何属性并返回到第一个视图，则其正确更新。

当我添加新位置或删除现有位置之一时，我的问题就开始了。当我回到第一视图时，消费者现有位置的数量不会更新。关闭并重新打开该应用程序后，所有数据都会正确显示。

正如我所说，我的核心数据模型有2个实体，如下所示：

实体：客户 id：字符串名称：字符串 locationList：[位置]（多个（位置），级联）

实体：位置 id：字符串 addess：字符串 fromCustomer：客户（一对一（客户），无效）

这是显示客户列表的视图：


struct CustomerList: View {

    @Environment(\.managedObjectContext) var moc

    @FetchRequest(
        entity: Customer.entity(),
        sortDescriptors: [
            NSSortDescriptor(keyPath: \Customer.name, ascending: true),
        ]
    ) var customerList: FetchedResults<Customer>

    var body: some View {

        VStack{
            CustomerArea
        }
        .navigationBarTitle(Text("Customers"), displayMode: .inline)
        .navigationBarItems(leading: btnCreate, trailing: btnNew)

    }

    var CustomerArea: some View {

        List{

            ForEach(customerList, id: \.id) { customer in

                NavigationLink(
                    destination: LocationList(selectedCustomer: customer)
                ) {
                    VStack(alignment: .leading){

                        Text("\(customer.name ?? "?")").font(.headline)

                        HStack{

                                    Spacer()
                                    Text("Locations: \(customer.locationList?.count ?? 0)")
                                        .font(.footnote)

                                }

                    }.padding()
                }

            }.onDelete(perform: self.removeCustomer)

        }

    }

    private func removeCustomer(at offsets: IndexSet) {

        for index in offsets {
            let obj = customerList[index]
            self.moc.delete(obj)
        }

        try? self.moc.save()

    }

}

最后，这是我的LocationList视图：


struct LocationList: View {

    @Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>

    @Environment(\.managedObjectContext) var moc

    var requestLocations : FetchRequest<Location>
    var locationList : FetchedResults<Location>{requestLocations.wrappedValue}

    var selectedCustomer: Customer

    init(selectedCustomer: Customer){

        self.selectedCustomer = selectedCustomer

        self.requestLocations = FetchRequest(
            entity: Location.entity(),
            sortDescriptors: [],
            predicate: NSPredicate(format: "fromCustomer.id == %@", selectedCustomer.id!)
        )

    }

    var btnNewLocation : some View { Button(action: {

        let object = Location(context: self.moc)
        object.id = UUID().uuidString
        object.address = UUID().uuidString
        object.fromCustomer = self.selectedCustomer

        try? self.moc.save()

    })  {
        Image(systemName: "plus.circle.fill")
        }
    }

    var body: some View {

        VStack{

            List{

                ForEach(locationList, id: \.id) { location in

                    VStack(alignment: .leading){
                        Text("\(location.address ?? "?")").font(.headline)
                        .onTapGesture {

                            print("Tapped and changed selected parent object")

                            self.selectedCustomer.name = "Changed"

                            try? self.moc.save()

                            self.presentationMode.wrappedValue.dismiss()

                        }

                    }.padding()

                }
                .onDelete(perform: removeLocation)

            }


        }
        .navigationBarTitle(Text("\(selectedCustomer.name ?? "?")"), displayMode: .inline)
        .navigationBarItems(trailing: btnNewLocation)
    }

    private func removeLocation(at offsets: IndexSet) {

        for index in offsets {

            let obj = locationList[index]

            self.moc.delete(obj)

        }

        try? self.moc.save()

    }

}

这是第一个视图。想象一下我触摸了最后一个项目：