Question

我创建了保存在核心数据中的客户端列表。我通过 AddView 添加了一些属性，现在我尝试使用不同的视图添加新属性。为了做到这一点，我明白我需要使用 ObservedObject 属性包装器，这样它就不会创建新客户端，而是更新现有客户端。这是代码：

import SwiftUI
import CoreData

struct TopicView: View {


@Environment(\.managedObjectContext) var managedObjectContext
@Environment (\.presentationMode) var presentationMode
@ObservedObject var topic: StudentData
@State var content = ""
@State private var show = false
@StateObject private var keyboard = Keyboard()

var body: some View {
Form{
            Section (header: Text("Topics covered")
                        .bold()
                        .padding(.all)
                        .font(.title3)) {
        

TextEditor(text: Binding(
                            get: {self.topic.content ?? ""},
                            set: {self.topic.content = $0 } ))
                    .frame(height: 250)
                    
    }
                 }.onTapGesture {
                    hideKeyboard()
                }
               }
             }
             Button ("Submit")
                 {
                    self.topic.content = self.content
                    self.topic.objectWillChange.send()

                    try? self.managedObjectContext.save()
                    self.presentationMode.wrappedValue.dismiss()
               }.foregroundColor(.white)

这是应该显示新属性的视图：

    import SwiftUI
import CoreData
import MapKit

struct StudentView: View {
    @Environment(\.managedObjectContext) var managedObjectContext
    @FetchRequest(entity: StudentData.entity(),
        sortDescriptors: [],
        animation: .spring())  var content: FetchedResults<StudentData>
    @Environment (\.presentationMode) var presentationMode
    @ObservedObject var topic: StudentData
    @State var showModalView = false
    @State private var showingSheet = false
    
    let myStudent: StudentData
  
var body: some View {
    
        NavigationView {
VStack{
                    Text("Topics Covered")
                        .font(.system(size: 30, weight: .bold, design: .rounded))
                        .foregroundColor(.red)
                        .padding(.horizontal)
                   Text("\(myStudent.content ?? "")")
                    .font(.title2)
                    .bold()
                    .foregroundColor(.white)
                    .padding(.horizontal) }}
                Spacer()
                Spacer()
}.sheet(isPresented: $showModalView, content: {
            TopicView(topic: topic)})

问题是，如果我在文本编辑器中输入一些文本而不保存它，那么它会在另一个视图中正确显示。但是，当我保存它时，它不会显示在其他视图中。我的保存代码有问题吗？

使用观察对象更新核心数据实体

0 个答案: