Firebase duplicate tableView when new date is added, updated or deleted - swift

Question

Whenever I add new data to Firebase or update the data in the Firebase console, my tableView data duplicates. The udemy tutorial I've followed never showed how to solve the issue. A Google search brought up my problem but non seemed to explain the root of the problem; I after the root of the issue and not just an answer. I'm learning as I go along but this one bugs me.
One answer mentioned the use of self.members.removeAll() but Im using Swift 3, where to put that and why?
My issue relates to this but that answer seemed vague and not really an answer. I have a configureCell() but what should be added?
I upvote most of my question's answers when someone explains and just adding an answer. What is happening and why, please? Do I need to reload/remove something in:
if let cell = tableView.dequeueReusableCellWithIdentifier("PostCell") as? PostCell{...}
Edited:
var expenses = [Expense]()
func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return expenses.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let expense = expenses[indexPath.row]
if let cell = tableView.dequeueReusableCell(withIdentifier: "expenseFeedCell") as? ExpenseFeedCell {
cell.selectionStyle = .none
cell.configureCell(expense: expense)
return cell
} else {
return ExpenseFeedCell()
}
}
And the Expense Class:
class Expense {
// Private variables
private var _date: Double!
private var _type: String!
private var _amount: Double!
private var _notes: String!
private var _expenseId: String!
// Setting up the getteres
var type: String {
return _type
}
var date: Double {
return _date
}
var amount: Double {
return _amount
}
var notes: String {
return _notes
}
var expenseId: String {
return _expenseId
}
init(type: String, date: Double, amount: Double, notes: String) {
self._type = type
self._date = date
self._amount = amount
self._notes = notes
}
init(expenseId: String, expenseData: [String: AnyObject]) {
self._expenseId = expenseId
if let type = expenseData["type"] as? String {
self._type = type
}
if let date = expenseData["date"] as? Double {
self._date = date
}
if let amount = expenseData["amount"] as? Double {
self._amount = amount
}
if let notes = expenseData["notes"] as? String {
self._notes = notes
}
}
}

Answer 1

If the firebase method you use to read data is called each time there is a new entry, you should remove the content of your data array before adding data on it.
So in the firebase method, start by having an empty array. After that you can treat with the snapchot and fill this same array.
Add a self.tableView.reloadData() to reload the view with new data in this array