缺少视图作为视图的祖先

Question

我有一个 login.swift 主要是：

import SwiftUI

class GlobalEnvironment: ObservableObject {

    @Published var accountId: Int = 0
}

struct Login: View {

    @EnvironmentObject var env: GlobalEnvironment

    @State private var username: String = ""
    @State private var password: String = ""

    @State var authenticationDdidFail: Bool = false
    @State var authenticationDidSucceed: Bool = false

    var body: some View {

        if env.accountId == 0 {
            return AnyView(LoginView(username: self.$username, password: self.$password, authenticationDdidFail: self.$authenticationDdidFail, authenticationDidSucceed: self.$authenticationDidSucceed))
        } else {
            return AnyView(ContentView().environmentObject(GlobalEnvironment()))
        }


    }
}
...

该文件在登录后设置 env.accontId，并且在 LoginView 中成功。

然后我有一个 data.swit 有：

struct Transaction: Codable, Identifiable {
    let id = UUID()
    var purpose: String
}

class Api {

    @EnvironmentObject var env: GlobalEnvironment

    func getTransactions(completion: @escaping ([Transaction]) -> ()) {

        guard let url = URL(string: "https://url.com/api.php?get_transactions&account=\(env.accountId)") else { return }

        URLSession.shared.dataTask(with: url) { (data, _, _) in
            let transactions = try! JSONDecoder().decode([Transaction].self, from: data!)
            DispatchQueue.main.async {
                completion(transactions)
            }

        }
        .resume()

}

API 从 Transactions.swift 调用：

import SwiftUI

struct ContentView: View {

    @EnvironmentObject var env: GlobalEnvironment

    @State var transactions: [Transaction] = []

    var body: some View {
        NavigationView {
            List(transactions) { transaction in
                Text(transaction.purpose)

                }
            .environmentObject(GlobalEnvironment())
            .onAppear {
                Api().getTransactions { (transactions) in
                    self.transactions = transactions
                }
            }
            .navigationBarTitle(Text("Transactions"))
        }
    }
}

我收到 guard let url = URL(string: "https://url.com/api.php?get_transactions&account=\(env.accountId)") else { return } 的错误 Thread 1: Fatal error: No ObservableObject of type GlobalEnvironment found. A View.environmentObject(_:) for GlobalEnvironment may be missing as an ancestor of this view.。

根据我的理解，将 GlobalEnvironment 添加到 Api class，应该可以，但没有。相反，我已经尝试将它添加到函数中，但它也不起作用。如您所见，将 .environmentObject() 添加到列表视图本身也是如此。

Answer 1

必须是：

  .environmentObject(self.env)

当然，在 SceneDelegate 或其他地方可能还有更多错误。

Answer 2

你可以尝试在 onAppear

的电话中发送你的 environmentObject

.onAppear 
{
    Api().getTransactions { (transactions) in
        self.transactions = transactions
    }.environmentObject(self.env)
}

缺少视图作为视图的祖先

A view is missing as an ancestor of a view

observable

swift

swift5

swiftui

observableobject