ios - 如何确认 Firestore 中的数据已快速附加？

Question

我使用下面的代码在 Swift IOS 中附加来自 Firestore 的数据，但是当我使用“print”函数检查是否检索到数据时，它不会打印任何实际数据它打印的只是以下详细信息，我应该如何确认数据是否准确附加？

代码

var messages: [DocumentSnapshot]! = []

 ref.addSnapshotListener { querySnapshot, error in
             guard let documents = querySnapshot?.documents else {
                 print("Error fetching documents: \(error!)")
                 return
             }

            for doc in documents {
              self.messages.append(doc)
              self.clientTable.insertRows(at: [IndexPath(row: self.messages.count-1, section: 0)], with: .automatic)
                //self.clientTable.reloadData()

            }

print(messages)

打印结果

Optional([<FIRQueryDocumentSnapshot: 0x60000123cbe0>, <FIRQueryDocumentSnapshot: 0x60000123ccd0>, <FIRQueryDocumentSnapshot: 0x60000123cd20>, <FIRQueryDocumentSnapshot: 0x60000123cd70>, <FIRQueryDocumentSnapshot: 0x60000123cdc0>, <FIRQueryDocumentSnapshot: 0x60000123ce10>, <FIRQueryDocumentSnapshot: 0x60000123ce60>, <FIRQueryDocumentSnapshot: 0x60000123cf00>, <FIRQueryDocumentSnapshot: 0x60000123cf50>, <FIRQueryDocumentSnapshot: 0x60000123cfa0>, <FIRQueryDocumentSnapshot: 0x60000123cff0>, <FIRQueryDocumentSnapshot: 0x60000123ceb0>, <FIRQueryDocumentSnapshot: 0x60000123d040>, <FIRQueryDocumentSnapshot: 0x60000123d090>, <FIRQueryDocumentSnapshot: 0x60000123d0e0>, <FIRQueryDocumentSnapshot: 0x60000123d130>, <FIRQueryDocumentSnapshot: 0x60000123d180>, <FIRQueryDocumentSnapshot: 0x60000123d1d0>, <FIRQueryDocumentSnapshot: 0x60000123d220>, <FIRQueryDocumentSnapshot: 0x60000123d270>, <FIRQueryDocumentSnapshot: 0x60000123d2c0>, <FIRQueryDocumentSnapshot: 0x60000123d310>, <FIRQueryDocumentSnapshot: 0x60000123d360>, <FIRQueryDocumentSnapshot: 0x60000123d3b0>, <FIRQueryDocumentSnapshot: 0x60000123d400>, <FIRQueryDocumentSnapshot: 0x60000123d450>, <FIRQueryDocumentSnapshot: 0x60000123d4a0>])

Answer 1

正如您在输出中看到的，文档为 FIRQueryDocumentSnapshot objects ，其中包含数据和有关结果的一些元数据。

要从快照中获取数据，请调用其 FIRQueryDocumentSnapshot.data method .

var messages: [DocumentSnapshot]! = []

ref.addSnapshotListener { querySnapshot, error in

     guard let documents = querySnapshot?.documents else {
         print("Error fetching documents: \(error!)")
         return
     }

    for doc in documents {
      self.messages.append(doc.data())
    }

    print(messages)
}

请注意，Firebase 文档 reading all documents from a collection 对此也有很好的描述。 ，所以我建议花一些时间研究一下。