SwiftUI@EnvironmentObject错误：此视图的祖先可能已丢失

我的第一个视图可以从API请求中获取所有数据，然后打开第二个视图更改API请求数据，它崩溃了

下面是错误

Fatal error: No ObservableObject of type NetworkManager found.
A View.environmentObject(_:) for NetworkManager may be missing as an ancestor of this view.: file /BuildRoot/Library/Caches/com.apple.xbs/Sources/Monoceros_Sim/Monoceros-39.3/Core/EnvironmentObject.swift, line 55
2019-11-07 12:00:01.961425-0800 EarthQuake[73703:5913116] Fatal error: No ObservableObject of type NetworkManager found.
A View.environmentObject(_:) for NetworkManager may be missing as an ancestor of this view.: file /BuildRoot/Library/Caches/com.apple.xbs/Sources/Monoceros_Sim/Monoceros-39.3/Core/EnvironmentObject.swift, line 55

这是一个swift文件，用于从API获取数据，然后将数据保存到POST

import Foundation
import Combine

final class NetworkManager: ObservableObject {

    @Published var posts = [Post]()


    func fetchData() {

         //some code to fetch data, then save to posts

    }

}

在我的第一个列表视图文件中：EarthQuakeList.swift

import SwiftUI

struct EarthQuakeList: View {

    @EnvironmentObject var networkManager: NetworkManager

    //@ObservedObject var networkManager = NetworkManager()

    var body: some View {

        NavigationView {
            List(networkManager.posts) { post in
                NavigationLink(destination: EarthQuakeDetail(detail: post.properties, location: post.locationCoordinate)) {
                    ListRow(magnitude: post.properties.mag ?? 0.0, place: post.properties.place)

                }

            }
          .navigationBarTitle(Text("Today"))      
            .navigationBarItems(

                    trailing:
                    VStack {

                        Button(action: {
                            print("Edit button tapped")
                            self.showEditPage.toggle()
                        }) {
                            //Top right icon
                            Image(systemName: "pencil.circle")
                                .resizable()
                                .frame(width: 20, height: 20, alignment: .center)
                        }.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

                        }

                    }




            )



        }
        .onAppear {
            //Call function to fetch data
            self.networkManager.fetchData()
        }
    }
}

import SwiftUI

struct EditPage: View {

    //@ObservedObject var networkManager = NetworkManager()

    @EnvironmentObject var networkManager: NetworkManager

    var body: some View {

        VStack {
            Text("Edite")


        }
        .onAppear(){

            //I called the same function to get data as in first view file, but it is not updating the list view 
            self.networkManager.fetchData()


        }

    }
}

import UIKit
import SwiftUI

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

        //Set up environment object
        let contentView = EarthQuakeList().environmentObject(NetworkManager())

        // Use a UIHostingController as window root view controller.
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(
                rootView: contentView
            )
            self.window = window
            window.makeKeyAndVisible()
        }
    }

.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

一切正常，我可以看到所有的数据，但当我在第二个视图文件中执行相同的操作时，我会将数据取回，但第一个视图中的数据不会更新

在我的第二个编辑视图文件中：EditPage.swift

import SwiftUI

struct EarthQuakeList: View {

    @EnvironmentObject var networkManager: NetworkManager

    //@ObservedObject var networkManager = NetworkManager()

    var body: some View {

        NavigationView {
            List(networkManager.posts) { post in
                NavigationLink(destination: EarthQuakeDetail(detail: post.properties, location: post.locationCoordinate)) {
                    ListRow(magnitude: post.properties.mag ?? 0.0, place: post.properties.place)

                }

            }
          .navigationBarTitle(Text("Today"))      
            .navigationBarItems(

                    trailing:
                    VStack {

                        Button(action: {
                            print("Edit button tapped")
                            self.showEditPage.toggle()
                        }) {
                            //Top right icon
                            Image(systemName: "pencil.circle")
                                .resizable()
                                .frame(width: 20, height: 20, alignment: .center)
                        }.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

                        }

                    }




            )



        }
        .onAppear {
            //Call function to fetch data
            self.networkManager.fetchData()
        }
    }
}

import SwiftUI

struct EditPage: View {

    //@ObservedObject var networkManager = NetworkManager()

    @EnvironmentObject var networkManager: NetworkManager

    var body: some View {

        VStack {
            Text("Edite")


        }
        .onAppear(){

            //I called the same function to get data as in first view file, but it is not updating the list view 
            self.networkManager.fetchData()


        }

    }
}

import UIKit
import SwiftUI

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

        //Set up environment object
        let contentView = EarthQuakeList().environmentObject(NetworkManager())

        // Use a UIHostingController as window root view controller.
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(
                rootView: contentView
            )
            self.window = window
            window.makeKeyAndVisible()
        }
    }

.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

SceneDelegate.swift

import SwiftUI

struct EarthQuakeList: View {

    @EnvironmentObject var networkManager: NetworkManager

    //@ObservedObject var networkManager = NetworkManager()

    var body: some View {

        NavigationView {
            List(networkManager.posts) { post in
                NavigationLink(destination: EarthQuakeDetail(detail: post.properties, location: post.locationCoordinate)) {
                    ListRow(magnitude: post.properties.mag ?? 0.0, place: post.properties.place)

                }

            }
          .navigationBarTitle(Text("Today"))      
            .navigationBarItems(

                    trailing:
                    VStack {

                        Button(action: {
                            print("Edit button tapped")
                            self.showEditPage.toggle()
                        }) {
                            //Top right icon
                            Image(systemName: "pencil.circle")
                                .resizable()
                                .frame(width: 20, height: 20, alignment: .center)
                        }.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

                        }

                    }




            )



        }
        .onAppear {
            //Call function to fetch data
            self.networkManager.fetchData()
        }
    }
}

import SwiftUI

struct EditPage: View {

    //@ObservedObject var networkManager = NetworkManager()

    @EnvironmentObject var networkManager: NetworkManager

    var body: some View {

        VStack {
            Text("Edite")


        }
        .onAppear(){

            //I called the same function to get data as in first view file, but it is not updating the list view 
            self.networkManager.fetchData()


        }

    }
}

import UIKit
import SwiftUI

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

        //Set up environment object
        let contentView = EarthQuakeList().environmentObject(NetworkManager())

        // Use a UIHostingController as window root view controller.
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(
                rootView: contentView
            )
            self.window = window
            window.makeKeyAndVisible()
        }
    }

.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

---

所以我希望第二个视图文件调用函数self.networkManager.fetchData（），从API调用中获取数据，然后更新第一个swift文件中的列表视图，视图未使用新数据更新

此问题似乎是由于在代码中使用了两个

NetworkManager

实例造成的

如果将此行添加到

网络管理器中

：

final类网络管理器：{
静态let shared=NetworkManager（）
}

然后更新两个视图中的引用，如下所示：

结构地震列表：{ @ObservedObject var networkManager=networkManager.shared … } 结构编辑页：{ @ObservedObject var networkManager=networkManager.shared … } 这将确保两个视图使用完全相同的对象访问信息。通过使用相同的对象，一个视图中的更新将导致另一个视图也被更新

一旦成功，我建议在SwiftUI中使用

.environmentObject（）

（），因为这样可以在应用程序中共享这些服务类型的相同实例

---

祝你的项目好运

整个问题很容易解决，只需添加self.networkManager@EarthQuakeList.swift

import SwiftUI

struct EarthQuakeList: View {

    @EnvironmentObject var networkManager: NetworkManager

    //@ObservedObject var networkManager = NetworkManager()

    var body: some View {

        NavigationView {
            List(networkManager.posts) { post in
                NavigationLink(destination: EarthQuakeDetail(detail: post.properties, location: post.locationCoordinate)) {
                    ListRow(magnitude: post.properties.mag ?? 0.0, place: post.properties.place)

                }

            }
          .navigationBarTitle(Text("Today"))      
            .navigationBarItems(

                    trailing:
                    VStack {

                        Button(action: {
                            print("Edit button tapped")
                            self.showEditPage.toggle()
                        }) {
                            //Top right icon
                            Image(systemName: "pencil.circle")
                                .resizable()
                                .frame(width: 20, height: 20, alignment: .center)
                        }.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

                        }

                    }




            )



        }
        .onAppear {
            //Call function to fetch data
            self.networkManager.fetchData()
        }
    }
}

import SwiftUI

struct EditPage: View {

    //@ObservedObject var networkManager = NetworkManager()

    @EnvironmentObject var networkManager: NetworkManager

    var body: some View {

        VStack {
            Text("Edite")


        }
        .onAppear(){

            //I called the same function to get data as in first view file, but it is not updating the list view 
            self.networkManager.fetchData()


        }

    }
}

import UIKit
import SwiftUI

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

        //Set up environment object
        let contentView = EarthQuakeList().environmentObject(NetworkManager())

        // Use a UIHostingController as window root view controller.
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(
                rootView: contentView
            )
            self.window = window
            window.makeKeyAndVisible()
        }
    }

.sheet(isPresented: $showEditPage) { 
                            return EditPage().environmentObject(self.networkManager)

我从文章中得到了原因和启发：

---

如果您使用的是sheet ore导航，您必须传递环境对象，这可能是swiftUI的一个错误，但在Xcode 11.5中它对我有效：

.sheet(isPresented: $show){
        mySheetView().environmentObject(self.myEnviromentObject)
}

---

请参阅本文中的“我的代码”，了解刷新2d中正在编辑的第一个视图的方法。希望对您有所帮助。@Asperi我使用的编码方式与您相同。ObservedObject和ObservedObject正如我从您的示例中看到的，您不需要—并没有任何东西强迫视图刷新。注意刷新状态是如何使用的。嗨@herzi，这很有效！非常感谢你！你是最棒的。我刚刚更新了我的问题，有

.environmentObject（）

，但是第二个视图没有更新第一个视图，它崩溃了，你能看一下吗？下一个问题的建议是：尝试发布一个新问题（可能在评论中链接它）。这样，其他人仍然可以要求“接受”响应。我正在使用此单例设计模式，我面临的问题是，这在当时没有解决。我正在使用此解决方案将environmentObject添加到我的.sheet中。但是，在我的.sheet中，我有指向进一步视图的导航链接。似乎我必须使用上面的解决方案，通过NavigationLink层次结构将environmentObject传递给每个后续视图，否则会导致无法观察到的对象崩溃。我本以为来自父.sheet的后续视图将是.sheet的子视图，从而继承环境对象，但事实似乎并非如此。有人对此有什么想法吗？OP的EarthQuakeList.swift与此回复中的建议完全相同。是否有人可以将问题和回答回填，以便为比较提供依据？OP的问题没有它是没有价值的。碰巧这些bug会被列在哪里/报告？你的解决方案为我解决了这个问题，但我没有正式的地方可以参考。你知道这可能在哪里吗？