我正在尝试用firstore和swiftui写一些测试，我可以创建和读取，但现在我不知道如何列出唯一的数据，

import SwiftUI
import Firebase

struct ContentView: View {
    @State private var uniqueData: [String] = []

    var body: some View {
        List(uniqueData, id: \.self) { data in
            Text(data)
        }
        .onAppear {
            fetchData()
        }
    }

    func fetchData() {
        let db = Firestore.firestore()
        db.collection("yourCollectionName").getDocuments { (snapshot, error) in
            if let error = error {
                print("Error getting documents: \(error)")
            } else {
                guard let documents = snapshot?.documents else { return }
                self.uniqueData = Array(Set(documents.map { $0.documentID }))
            }
        }
    }
}