Firebase、Cloud Firestore - SwiftUI在视图中显示集合数据

import SwiftUI
import Firebase
import FirebaseFirestoreSwift

struct ContentView: View {
    @StateObject private var viewModel = FirestoreViewModel()
    
    var body: some View {
        List(viewModel.documents) { document in
            Text(document.title)
        }
        .onAppear {
            viewModel.fetchDocuments()
        }
    }
}

struct Document: Identifiable, Codable {
    @DocumentID var id: String?
    var title: String
}

class FirestoreViewModel: ObservableObject {
    @Published var documents: [Document] = []
    
    private var db = Firestore.firestore()
    
    func fetchDocuments() {
        db.collection("documents").addSnapshotListener { querySnapshot, error in
            guard let documents = querySnapshot?.documents else {
                print("Error fetching documents: \(error?.localizedDescription ?? "Unknown error")")
                return
            }
            
            self.documents = documents.compactMap { document in
                try? document.data(as: Document.self)
            }
        }
    }
}