update Firebase deleted table cell - ios

Question

I have a node in Firebase database. its a node for the messaging portion in my App. It is a private chat. I want to incorporate the ability for one user to delete his messages but the messages still remain in the other user's app. so I created a fan out property.
override func didPressSend(_ button: UIButton!, withMessageText text: String!, senderId: String!, senderDisplayName: String!, date: Date!) {
let convoRef = FIRDatabase.database().reference().child("messages").child(convoId!)
let itemRef = rootRef.child("messages").child(convoId!).childByAutoId() // 1
let messageItem = [ // 2
"senderId": senderId!,
"ReceiverId": senderDisplayName!,
"text": text!,
"timestamp": NSDate().timeIntervalSince1970,
"convoId": convoId!
] as [String : Any]
// itemRef.setValue(messageItem) // 3
itemRef.updateChildValues(messageItem) { (error, convoRef) in
if error != nil{
print(error)
return
}
let userMessagesRef = FIRDatabase.database().reference().child("user-messages").child(self.senderId!)
let messageId = itemRef.key
userMessagesRef.updateChildValues([messageId: 1])
let userMessagesRefs = FIRDatabase.database().reference().child("user-messages").child(self.senderDisplayName!)
let messagedId = itemRef.key
userMessagesRefs.updateChildValues([messagedId: 1])
}
}
And then i created the option to delete the message cell.
override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
guard let uid = FIRAuth.auth()?.currentUser?.uid else {
return
}
let ref = FIRDatabase.database().reference().child("user-messages").child(uid)
ref.observe(.childAdded, with: { (snapshot) in
self.messageId = snapshot.key
FIRDatabase.database().reference().child("user-messages").child(uid).child( self.messageId!).removeValue(completionBlock: { (error, ref) in
if error != nil {
print("error \(error)")
}else{
}
})})
self.messagesDictionary.removeValue(forKey: uid)
self.handleReloadTable()
}
But when the table reloads,it crashes
func loadData()
{
guard let uid = FIRAuth.auth()?.currentUser?.uid else {
return
}
let ref = FIRDatabase.database().reference().child("user-messages").child(uid)
ref.observe(.childAdded, with: { (snapshot) in
self.messageId = snapshot.key
})
FIRDatabase.database().reference().child("messages").observeSingleEvent(of: .value, with: { (snapshot:FIRDataSnapshot) in
if let postsDictionary = snapshot .value as? [String: AnyObject] {
for post in postsDictionary {
let messages = post.value as! [String: AnyObject]
for (id, value) in messages {
let info = value as! [String: AnyObject]
let convoId = info["convoId"]
let toId = info["ReceiverId"] as! String!
let fromId = info["senderId"] as! String!
if (toId == self.loggedInUserUid || fromId == self.loggedInUserUid) {
let ref = FIRDatabase.database().reference().child("messages").child(convoId as! String).child(self.messageId!)
ref.observeSingleEvent(of: .value, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: AnyObject] {
let message = Message(dictionary: dictionary)
// self.messages.append(message)
if let receiver = message.convoId {
self.messagesDictionary[receiver] = message
self.messages = Array(self.messagesDictionary.values)
print(self.messages)
self.messages.sort(by: { (message1, message2) -> Bool in
return (message1.timestamp?.int32Value)! > (message2.timestamp?.int32Value)!
})
}
//this will crash because of background thread, so lets call this on dispatch_async main thread
DispatchQueue.main.async(execute: {
self.MessageTableView.reloadData()
})
}
}, withCancel: nil)}
}
}}})
}
And says messageId is an optional value.