swiftui/coredata/master/detail(带编辑)/xcode 11-beta 5

正在处理示例应用程序。我们的目标是从master中的coredata中提取一个列表,然后单击其中一个列表转到一个细节,在那里您可以编辑信息并保存。当您编辑细节中的“名称”时,它不仅会更新细节以反映更改,而且还会反映主控形状上的更改。我已经尝试了很多方法来实现这一点,但是到目前为止还没有找到答案。

// Code generation is turned OFF in the xcdatamodeld file

public class EntityName: NSManagedObject, Identifiable {
   @NSManaged public var name: String
   @NSManaged public var active: Bool
}

extension EntityName {
    static func allEntityNameFetchRequest() -> NSFetchRequest<EntityName> {
        let request: NSFetchRequest<EntityName> = EntityName.fetchRequest() as! NSFetchRequest<EntityName>
        request.sortDescriptors = [NSSortDescriptor(key: "name", ascending: true)]
        return request
   }
}


struct MasterView: View {

    @Environment(\.managedObjectContext) var managedObjectContext
    @FetchRequest(fetchRequest: EntityName.allEntityNameFetchRequest()) var allEntityNames: FetchedResults<EntityName>


    var body: some View {
        NavigationView {
            List {
                ForEach(self.allEntityNames) { entityName in
                NavigationLink(destination: DetailView(entityName: entityName)) {
                    VStack(alignment: .leading) {
                        Text(entityName.name)
                            .font(.headline)
                        Text(String(entityName.active))
                            .font(.subheadline)
                    }
                }
            }
        }
    }
    .onAppear() {
        // Just want to populate the Core Data to have a few to work with
        if self.allEntityNames.count == 0 {
            for _ in 1...3 {
                let newEntry = EntityName(context: self.managedObjectContext)
                newEntry.name = "New Entry"

                try! self.managedObjectContext.save()
            }
         }
      }
   }
}

struct DetailView: View {

   var entityName = EntityName()

   var body: some View {
       VStack {
           Text("Name: \(entityName.name)")
           Text("Active: \(String(entityName.active))")

           // What I'd like to do now:
              //TextField("", text: $entityName.name)
              //Toggle(isOn: $entityName.active)
       }
   }
}