如何在Swift中读取Firestore时间戳

import Firebase
import FirebaseFirestore

let db = Firestore.firestore()

let docRef = db.collection("collectionName").document("documentID")

docRef.getDocument { (document, error) in
    if let document = document, document.exists {
        let timestamp = document.data()?["timestampField"] as? Timestamp
        // 处理时间戳数据
    } else {
        print("文档不存在")
    }
}

if let timestamp = timestamp {
    let date = timestamp.dateValue() // 将时间戳转换为Date对象
    let seconds = timestamp.seconds // 获取时间戳的秒数
    let nanoseconds = timestamp.nanoseconds // 获取时间戳的纳秒数
    // 进一步处理时间戳数据
}