childAdded and childChanged UITableView handling with Firebase. Handles both live cell updates and new children.

FirebaseObservers.swift

// Database Reference
var ref: DatabaseReference!
var handle: UInt!
var updateHandler: UInt!

// Local store
var wishes = [Wish]() 

override func viewWillAppear(_ animated: Bool) {
  super.viewWillAppear(animated)

  // Observe new wishes
  self.handle = self.ref.observe(.childAdded, with: { snapshot in
      do {
          let wish = try Wish(snapshot: snapshot)

          // Replace with new data if exists
          if let index = self.wishes.index(where: { $0.ref?.key == wish.ref?.key }) {
              self.wishes[index] = wish

              // Reload UITableViewCell
              let indexPath = IndexPath(row: index, section: 0)
              self.tableView.reloadRows(at: [indexPath], with: .automatic)
          }

          // Append (if not exists)
          else if !self.wishes.contains(wish) {
              self.wishes.append(wish)

              // Order descending
              self.wishes.sort(by: { $0.createdAt > $1.createdAt })
          }
      }
      catch let error {
          print(error)
      }

      self.tableView.reloadData()
  })

  // Observe wish updates
  self.updateHandler = self.ref.observe(.childChanged, with: { snapshot in
      do {
          let wish = try Wish(snapshot: snapshot)

          // Find wish and update
          if let index = self.wishes.index(where: { $0.ref?.key == wish.ref?.key }) {

              // Update wish
              self.wishes[index] = wish

              // Reload UITableViewCell
              let indexPath = IndexPath(row: index, section: 0)
              self.tableView.reloadRows(at: [indexPath], with: .automatic)
          }
      }
      catch let error {
          print(error)
      }

      self.tableView.reloadData()
  })
}

override func viewDidDisappear(_ animated: Bool) {
    super.viewDidDisappear(animated)

    // Remove observer
    self.ref.removeObserver(withHandle: self.handle)
    self.ref.removeObserver(withHandle: self.updateHandler)
}

will you please show the structure of your data model Wish