strange tableView.reloadData() behavior - swift

Question

I am trying to make simple firebase realtime chat app in swift. I have node in my database where number of unread messages is stored/
I have custom tableview cell which has label for displaying number of unread messages
class UserCell: UITableViewCell {
var message: Message? {
didSet {
setNumberOfUnreadMessages()
}
fileprivate func setNumberOfUnreadMessages() {
if let partnerId = message?.chatPartnerId(), let selfId = message?.selfId() {
let unreadMessagesRef = Database.database().reference().child("unread-messages").child(selfId).child(partnerId).child("numberOfUnreadMessages")
unreadMessagesRef.observe(.value, with: { (snapshot) in
if let count = snapshot.value as? Int {
self.unreadMessagesCountLabel.isHidden = false
self.unreadMessagesCountLabel.text = String(count)
} else {
self.unreadMessagesCountLabel.isHidden = true
}
print(snapshot)
}, withCancel: nil)
}
}
My tableView
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: cellId, for: indexPath) as? UserCell
let message = messages[indexPath.row]
cell?.message = message
return cell!
}
func observeUserMessages() {
guard let uid = Auth.auth().currentUser?.uid else { return }
// getting reference to current user's node
let ref = Database.database().reference().child("user-messages").child(uid)
ref.observe(.childAdded, with: { (snapshot) in
let userId = snapshot.key
// getting reference to partners node in user's node
let userMessagesRef = Database.database().reference().child("user-messages").child(uid).child(userId)
userMessagesRef.observe(.childAdded, with: { (snapshot) in
if let dictionary = snapshot.value as? [String:AnyObject] {
let message = Message(dictionary: dictionary)
if let chatPartnerId = message.chatPartnerId() {
self.messagesDictionary[chatPartnerId] = message
}
self.attemptReloadOfTableView()
}
}, withCancel: nil)
}, withCancel: nil)
ref.observe(.childRemoved, with: { (snapshot) in
print(snapshot.key)
self.messagesDictionary.removeValue(forKey: snapshot.key)
self.attemptReloadOfTableView()
}, withCancel: nil)
}
// Big thank to Brian Woong)))))
var timer: Timer?
private func attemptReloadOfTableView() {
self.timer?.invalidate()
self.timer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(self.handleReloadTableView), userInfo: nil, repeats: false)
}
#objc func handleReloadTableView() {
self.messages = Array(self.messagesDictionary.values)
self.messages.sort(by: { (message1, message2) -> Bool in
return (message1.timeStamp?.intValue)! > (message2.timeStamp?.intValue)!
})
DispatchQueue.main.async {
self.tableView.reloadData()
}
}
When I start my app every tableView.cell shows correct number of unread messages from database. When I start to send messages, tableView reloads and begins to show the number of unread messages from sender not only on his cell, but on ALL cells. Moreover in console I see that it gets more and more snapshots from database with every upcoming message.
What happens? How to fix this strange bug?

Answer 1

let unreadMessagesRefHandle = unreadMessagesRef.observe(.value, with: { (snapshot) in
if let count = snapshot.value as? Int {
self.unreadMessagesCountLabel.isHidden = false
self.unreadMessagesCountLabel.text = String(count)
} else {
self.unreadMessagesCountLabel.isHidden = true
}
print(snapshot)
}, withCancel: nil)
unreadMessagesRef.removeObserver(withHandle: unreadMessagesRefHandle)