delete table view cell from Firebase - ios

Question

I have a chat app. A user can choose another user in the app to chat with. Once a user sends a message to another user, their appended messages is displayed in a table view controller and when you click on the table view cell you are segued into a detailed controller.
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
JSQSystemSoundPlayer.jsq_playMessageSentSound() // 4
finishSendingMessage() // 5
isTyping = false
}
So only the two users chatting can view the messages. But I want one user to be able to delete the table view cell in their app (the messages) but when they do that it deletes in Firebase and that means it deletes in the other user's app too but I want it to only delete in the user that deleted the message. Here is how the messages are appended to be displayed in the tableview controller
func loadData()
{
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)
ref.observe(.childAdded, with: { (snapshot) in
if let dictionary = snapshot.value as? [String: AnyObject] {
let message = Message(dictionary: dictionary)
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)}
}
}}})
}

Answer 1

If an update is made to a Firebase Realtime Database node, then any user reading on that node would see the same value ( if the security rules allow the user to read that node ). So, to answer your question - you can't really make user specific updates to a database path.
Having said that, in your case, you can do one of the following :-
You can delete what you're trying to delete on the client side, so that it won't be visible any longer. However, that won't delete the data in the database, and you would see it again the next time you download from the same path.
You can have separate conversation paths for both the users, and store the same messages in both these locations instead of a common one. In this method, you'd be duplicating data. But if you want to make user-specific changes, then this would more than do it for you.