我正在使用Swift 4.2和FireStore中的MessageKit库创建一个聊天应用程序。
我的问题是我无法在addSnapshotListener类中存储通过使用Message进行实时通信获取的数据并确认了该类的内容，但是我认为这是不对的。
messageListener工作正常。执行handleDocumentChange时，它返回nil。
我用document.data ()检查了返回值，但是返回了值。
我该如何通过引用类来存储值？
guard var message = Message (document: change.document) else {
print ("return Message")
return
}
为FireStore输入的数据如下
{
"channels": [{
"MOuL1sdbrnh0x1zGuXn7": { // channel id
"name": "Puppies",
"thread": [{
"3a6Fo5rrUcBqhUJcLsP0": { // message id
"content": "Wow, that's so cute!",
"created": "May 12, 2018 at 10:44:11 PM UTC-5",
"senderID": "YCrPJF3shzWSHagmr0Zl2WZFBgT2",
"senderUsername": "naturaln0va",
"recipientProfilePictureURL":"URL",
"recipientID":"ezample",
"recipientUsername" :"A"
"recipientProfilePictureURL":"aaaaa"
},
}]
},
}]
}
这是我的消息类别：
class Message: MessageType {
var id: String?
var sentDate: Date
var kind: MessageKind
lazy var sender: Sender = Sender(id: atcSender.uid ?? "No Id", displayName: atcSender.uid ?? "No Name")
var atcSender: User
var recipient: User
var messageId: String {
return id ?? UUID().uuidString
}
var image: UIImage? = nil
var downloadURL: URL? = nil
let content: String
init(messageId: String, messageKind: MessageKind, createdAt: Date, atcSender: User, recipient: User) {
self.id = messageId
self.kind = messageKind
self.sentDate = createdAt
self.atcSender = atcSender
self.recipient = recipient
switch messageKind {
case .text(let text):
self.content = text
default:
self.content = ""
}
}
init(user: User, image: UIImage) {
self.image = image
content = ""
sentDate = Date()
id = nil
self.kind = MessageKind.text("xxx")
self.atcSender = user
self.recipient = user
}
init?(document: QueryDocumentSnapshot) {
let data = document.data()
guard let sentDate = data["created"] as? Date else {
return nil
}
guard let senderID = data["senderID"] as? String else {
return nil
}
guard let senderUsername = data["senderUsername"] as? String else {
return nil
}
guard let senderProfilePictureURL = data["senderProfilePictureURL"] as? String else {
return nil
}
guard let recipientID = data["recipientID"] as? String else {
return nil
}
guard let recipientUsername = data["recipientUsername"] as? String else {
return nil
}
guard let recipientProfilePictureURL = data["recipientProfilePictureURL"] as? String else {
return nil
}
id = document.documentID
self.sentDate = sentDate
self.atcSender = User(uid: senderID, username: senderUsername, firstname: "", lastname: "", email: "", profileUrl: senderProfilePictureURL)
self.recipient = User(uid: recipientID, username: recipientUsername, firstname: "", lastname: "", email: "", profileUrl: recipientProfilePictureURL)
if let content = data["content"] as? String {
self.content = content
downloadURL = nil
} else if let urlString = data["url"] as? String, let url = URL(string: urlString) {
downloadURL = url
self.content = ""
} else {
return nil
}
self.kind = MessageKind.text(content)
}
required init(jsonDict: [String: Any]) {
fatalError()
}
var description: String {
return self.messageText
}
var messageText: String {
switch kind {
case .text(let text):
return text
default:
return ""
}
}
var channelId: String {
let id1 = (recipient.username ?? "")
let id2 = (atcSender.username ?? "")
return id1 < id2 ? id1 + id2 : id2 + id1
}
}
extension Message: DatabaseRepresentation {
var representation: [String : Any] {
var rep: [String : Any] = [
"created": sentDate,
"senderID": atcSender.uid ?? "",
"senderUsername": atcSender.username ?? "",
"senderProfilePictureURL": atcSender.profileUrl ?? "",
"recipientID": recipient.uid ?? "",
"recipientUsername": recipient.username ?? "",
"recipientProfilePictureURL": recipient.profileUrl ?? "",
]
if let url = downloadURL {
rep["url"] = url.absoluteString
} else {
rep["content"] = content
}
return rep
}}extension Message: Comparable {
static func == (lhs: Message, rhs: Message) -> Bool {
return lhs.id == rhs.id
}
static func < (lhs: Message, rhs: Message) -> Bool {
return lhs.sentDate < rhs.sentDate
}
}
ChatViewController：
import UIKit
import MessageKit
import MessageInputBar
import Firebase
import FirebaseFirestore
import FirebaseAuth
class ChatViewController: MessagesViewController {
private let db = Firestore.firestore()
private var reference: CollectionReference?
private var messages: [Message] = []
private var messageListener: ListenerRegistration?
private let user: User
private let channel: Channel
let uid = Auth.auth().currentUser?.uid
init(user: User, channel: Channel) {
self.user = user
self.channel = channel
super.init(nibName: nil, bundle: nil)
title = channel.name
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
deinit {
messageListener?.remove()
}
override func viewDidLoad() {
super.viewDidLoad()
guard let id = channel.id else {
navigationController?.popViewController(animated: true)
return
}
reference = db.collection(["channels", id, "thread"].joined(separator: "/"))
// reference?.addSnapshotListener { querySnapshot, error in
// guard let snapshot = querySnapshot else {
// print("Error fetching snapshots: \(error!)")
// return
// }
// snapshot.documentChanges.forEach { diff in
// if (diff.type == .added) {
// print("New city: \(diff.document.data())")
// }
// if (diff.type == .modified) {
// print("Modified city: \(diff.document.data())")
// }
// if (diff.type == .removed) {
// print("Removed city: \(diff.document.data())")
// }
// }
// }
messageListener = reference?.addSnapshotListener { querySnapshot, error in
guard let snapshot = querySnapshot else {
print("Error listening for channel updates: \(error?.localizedDescription ?? "No error")")
return
}
snapshot.documentChanges.forEach { change in
self.handleDocumentChange(change)
print("handleDocumentChange")
}
}
self.navigationItem.title = title
messageInputBar.delegate = self
messagesCollectionView.messagesDataSource = self
messagesCollectionView.messagesLayoutDelegate = self
messagesCollectionView.messagesDisplayDelegate = self
messageInputBar.sendButton.tintColor = UIColor.lightGray
//scrollsToBottomOnKeyboardBeginsEditing = true // default false
//maintainPositionOnKeyboardFrameChanged = true // default false
}
private func save(_ message: Message) {
reference?.addDocument(data: message.representation) { error in
if let e = error {
print("Error sending message: \(e.localizedDescription)")
return
}
self.messagesCollectionView.scrollToBottom()
}
}
private func insertNewMessage(_ message: Message) {
guard !messages.contains(message) else {
return
}
messages.append(message)
messages.sort()
let isLatestMessage = messages.index(of: message) == (messages.count - 1)
let shouldScrollToBottom = messagesCollectionView.isAtBottom && isLatestMessage
messagesCollectionView.reloadData()
if shouldScrollToBottom {
DispatchQueue.main.async {
self.messagesCollectionView.scrollToBottom(animated: true)
}
}
}
private func handleDocumentChange(_ change: DocumentChange) {
guard var message = Message(document: change.document) else {
print("return Message")
return
}
switch change.type {
case .added:
print("add Message")
insertNewMessage(message)
default:
break
}
}
}
控制台打印
New city: ["senderUsername": panyayan,
"senderID": RAMIqHAVeoU4TKkm3FDw7XUwgym2,
"created": FIRTimestamp:seconds=1544623185 nanoseconds=412169933>,
"recipientUsername": panyayan,
"content": AAA,
"recipientID": RAMIqHAVeoU4TKkm3FDw7XUwgym2,
"recipientProfilePictureURL": https:,
"senderProfilePictureURL": https:]
return Message
handleDocumentChange
答案 0 :(得分：0)
不知道您是否仍然需要它，但是：
document.data()字段created是FIRTimestamp。
当您尝试初始化Message对象时，使用
guard let sentDate = data["created"] as? Date else {
return nil
}
那可能是一个原因，为什么您的对象为nil。 尝试类似
guard let sentTimestamp = data["created"] as? Timestamp else {
return nil
}
...
self.sentDate = sentTimestamp.dateValue()