Swift Firebase: Appropriate place to reloadData() - swift

Question

I am attempting to reloadData() after fetching data in an async operation from Firebase. I am having difficulty finding the appropriate location to do the reloadData() as at different location, it either refreshes one section of the tableView and not the other, or it does not refresh at all, or worse, the refresh jumbles up the dataset.
Here is my code so far, and a description of the outcome when I reloadData() at that particular location:
func getData() {
DispatchQueue.main.async {
self.titleView.setTitle(viewController: self, animate: true, title: "Updating...")
}
ref.child("conversations").child(userUID).observeSingleEvent(of: .value) { (snapshot) in
for snap in snapshot.children {
let snapDatasnapshot = snap as! DataSnapshot
let snapValues = snapDatasnapshot.value as! [String: AnyObject]
let recipientUID = snapDatasnapshot.key
for (key, value) in snapValues {
let conversationStartTime = value["conversationStartTime"] as! Double
if calculateMinutesLeft(conversationStartTime) >= 0 {
let messagesDatasnapshot = snapDatasnapshot.childSnapshot(forPath: shoutoutID).childSnapshot(forPath: "messages")
let messagesArray = messagesDatasnapshot.value as! [String: AnyObject]
self.startTimeDictionary[shoutoutID] = conversation
for message in messagesArray {
let messageID = message.key
self.ref.child("messages").child(messageID).observeSingleEvent(of: .value, with: { (messagesSnapshot) in
let dictionary = messagesSnapshot.value as! [String: AnyObject]
let timestamp = dictionary["timestamp"] as! Double
let readReceipt = dictionary["readReceipt"] as! Bool
if let messageText = dictionary["message"] {
let message = messageText as! String
let m = Message(fromUserUID: self.userUID, message: message, timestamp: timestamp, recipientUserUID: recipientUID, imageUrl: nil, readReceipt: readReceipt)
self.messagesDictionary[conversation] = m
self.messages = Array(self.messagesDictionary.values)
}
//Location 1
DispatchQueue.main.async {
self.tableView.reloadData()
self.titleView.setTitle(viewController: self, animate: false, title: "Chats")
}
})
}
} else {
//Expired Convos
self.expiredConversations.append(conversation)
//Location 2
DispatchQueue.main.async {
self.tableView.reloadData()
self.titleView.setTitle(viewController: self, animate: false, title: "Chats")
}
}
}
}
if self.messages.isEmpty && self.expiredConversations.isEmpty {
self.titleView.setTitle(viewController: self, animate: false, title: "Chats")
}
//Location 3
DispatchQueue.main.async {
self.tableView.reloadData()
self.titleView.setTitle(viewController: self, animate: false, title: "Chats")
}
}
//Location 4
DispatchQueue.main.async {
self.tableView.reloadData()
self.titleView.setTitle(viewController: self, animate: false, title: "Chats")
}
}
The messages will be displayed in section 0 of the tableView while expiredConversations will be displayed in section 1 of the tableView.
My current implementation is at location 1 and 2. Doing so correctly reloads both sections of the table but will tend to jumble the data up when refreshed multiple times, or when tableView size gets too large. Otherwise:
At location 1 only, will refresh just section 0
At location 2 only, will refresh just section 1
At location 3 and 4, will refresh all sections, but give empty messages and expiredConversations
Any advice where is the best or ideal location to reloadData()? Or could my implementation be wrong totally?
EDIT: tableViewDelegate and tableViewDatasource
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
switch section {
case 0:
if messages.isEmpty {
return 1
} else {
return messages.count
}
case 1:
return expiredConversations.count
default:
return 0
}
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
switch indexPath.section {
case 0:
if messages.isEmpty {
let noConversationsCell = tableView.dequeueReusableCell(withIdentifier: "noConversationsCell", for: indexPath) as! NoActiveConversationsTableViewCell
noConversationsCell.isUserInteractionEnabled = false
return noConversationsCell
} else {
let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! ChatLogTableViewCell
let message = messages[indexPath.row]
let conversation = conversations[indexPath.row]
//All the data model thing to populate the cells
return cell
}
case 1:
let expiredConversationsCell = tableView.dequeueReusableCell(withIdentifier: "expiredConversationsCell", for: indexPath) as! ExpiredConversationsTableViewCell
let conversation = expiredConversations[indexPath.row]
//All the data model thing to populate the cells
return expiredConversationsCell
default:
return UITableViewCell()
}
}