将observedObject放入列表

Question

我从我的api中获取数据并为它们创建一个类。我可以使用swifyJSON来正确地初始化它们。问题是，当我把我的observedObject放在一个列表中时，它只能正确显示一次。在我更改视图后，它将崩溃。(这个视图在tabView中)有人知道我的getAllNotification()应该把view.onAppear()或List.onAppear()放在哪里吗？谢谢！！

class ManagerNotification : Identifiable, ObservableObject{
@Published var id = UUID()
var notifyId : Int = 0
var requestId : Int = 0
var requestName: String = ""
var groupName : String = ""
//        var imageName: String { return name }

init(jsonData:JSON) {
    notifyId = jsonData["notifyId"].intValue
    requestId = jsonData["requestId"].intValue
    requestName = jsonData["requestName"].stringValue
    groupName = jsonData["groupName"].stringValue
}

}

import SwiftUI
import SwiftyJSON


struct NotificationView: View {
var roles = ["userNotification", "managerNotification"]
@EnvironmentObject var userToken:UserToken

@State var show = false
@State private var selectedIndex = 0

@State var userNotifications : [UserNotification] = [UserNotification]()
@State var managerNotifications : [ManagerNotification] = [ManagerNotification]()

var body: some View {


        VStack {
            Picker(selection: $selectedIndex, label: Text(" ")) {
                        ForEach(0..<roles.count) { (index) in
                            Text(self.roles[index])
                        }
                    }
            .pickerStyle(SegmentedPickerStyle())
            containedView()
            Spacer()

    }
               .onAppear(perform: getAllNotification)
}

func containedView() -> AnyView {
   switch selectedIndex {
   case 0:
       return AnyView(
            List(userNotifications) { userNotification in
                UserNotificationCellView(userNotification: userNotification)
            }
        )

   case 1:

      return AnyView(
        List(managerNotifications) { managernotification in
          ManagerNotificationCellView(managerNotification : managernotification)
        }
        .onAppear(perform: getManagerNotification)


    )

   default:
    return AnyView(Text("22").padding(40))
    }

}

func getAllNotification(){
//        if (self.userNotifications.count != 0){
//            self.userNotifications.removeAll()
//        }
//    I think the crash was in here, because when i don't use removeAll().
//    It works fine, but i don't want every times i change to this view. my array will be longer and 
//    longer

      if (self.managerNotifications.count != 0){
          self.managerNotifications.removeAll()
      }

    NetWorkController.sharedInstance.connectApiByPost(api: "/User/email", params: ["token": "\(self.userToken.token)"])
    {(jsonData) in
        if let result = jsonData["msg"].string{
            print("eeee: \(result)")
            if(result == "you dont have any email"){

            }else if(result == "success get email"){
                if let searchResults = jsonData["mail"].array {
                    for notification in searchResults {
                        self.userNotifications.append(UserNotification(jsonData: notification))
                    }
                }
            }
        }

    }

    NetWorkController.sharedInstance.connectApiByPost(api: "/Manager/email", params: ["token": "\(self.userToken.token)"])
           {(jsonData) in
               if let result = jsonData["msg"].string{
                   print("eeee: \(result)")
                   if(result == "you dont have any email"){

                   }else if(result == "success get email"){
                       if let searchResults = jsonData["mail"].array {
                           for notification in searchResults {
                               self.managerNotifications.append(ManagerNotification(jsonData: notification))
                           }
                       }

                   }
               }

           }
}

func getManagerNotification(){

//        if (self.managerNotifications.count != 0){
//            self.managerNotifications.removeAll()
//        }
    print(self.managerNotifications.count)
    NetWorkController.sharedInstance.connectApiByPost(api: "/Manager/email", params: ["token": "\(self.userToken.token)"])
    {(jsonData) in
        if let result = jsonData["msg"].string{
            print("eeee: \(result)")
            if(result == "you dont have any email"){

            }else if(result == "success get email"){
                if let searchResults = jsonData["mail"].array {
                    for notification in searchResults {
                        self.managerNotifications.append(ManagerNotification(jsonData: notification))
                    }
                }
            }
        }

    }
}

}

错误消息

仅警告一次: UITableView被告知布局其可见单元格和其他内容，而不是在视图层次结构中(表视图或其超级视图之一尚未添加到窗口)。这可能会通过强制表格视图内的视图在没有准确信息(例如表格视图边界、特征集合、布局边距、安全区域插入等)的情况下加载和执行布局而导致错误，并且还将由于额外的布局传递而导致不必要的性能开销。在UITableViewAlertForLayoutOutsideViewHierarchy处创建一个符号断点，以便在调试器中捕获此操作并查看导致此操作的原因，这样您就可以在可能的情况下完全避免此操作，或者将其推迟到将表视图添加到窗口中。原因：‘尝试删除节0，但在更新之前只有0个节’

Answer 1

我认为您对@State和@ObservebableObject的角色感到困惑；它不像MVC那样，在MVC中用SwiftUI.View替换ViewController，就像您在示例中尝试做的那样。相反，视图应该是某个本地@State和/或外部@ObservedObject的函数。这更接近于MVVM，在MVVM中，您的@ObservedObject类似于ViewModel，视图将根据ObservableObject上的@Published属性的更改进行自我重建。

TLDR:将您的获取逻辑移动到一个ObservableObject，并使用@Published来允许视图订阅结果。这里有一个例子：https://github.com/joshuajhomann/TVMaze-SwiftUI-Navigation