问为什么已删除的tableView节的属性会被缓存？

EN

     var media = [Media]()

       override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

     let cell = tableView.dequeueReusableCell(withIdentifier: Storyboard.mediaCell, for: indexPath) as! MediaTableViewCell
     cell.delegate = self

  if firstMessagesLoaded == false {

         //hide some buttons and disable userInteraction
        cell.isUserInteractionEnabled = true
        return cell
    }

  if firstMessagesLoaded == true {
    //it turns out I have to enable userInteraction again here, otherwise it will remain disabled even though the section at this indexPath was deleted previously
    // cell.isUserInteractionEnabled = false
      return cell
    }
   }


 func fetchMediaChildAdded() {
    let newMedia = Media() //received from database ...

      //when new media is fetched, remove the placeholder media from array, delete the section and add new data
     if self.firstMessagesLoaded == false {
           self.firstMessagesLoaded = true

            //remove the mediaPlaceholder and delete it's section
        self.tableView.beginUpdates()
            self.media.remove(at: 0)
            let indexVal = IndexSet(integer: 0)
            self.tableView.deleteSections(indexVal, with: .automatic)
        self.tableView.endUpdates()
           if !self.media.contains(newMedia) {
            self.media.insert(newMedia, at: 0)
        }
 }