Fix bug: Get user data in main queue to make sure user array is not empty when layout cell

Author: hoangtaiki

Example/Source/MessageViewController.swift

@@ -22,13 +22,17 @@ class MessageViewController: ChatViewController {
  setupData()
  bindViewModel()
 
+ // Get user data firstly
+ DispatchQueue.main.async { [weak self] in
+ self?.viewModel.getUserData()
+ }
  viewModel.firstLoadData { [weak self] in
  DispatchQueue.main.async {
  self?.updateUI()
  }
  }
  }
-
+ 
  override func numberOfSections(in tableView: UITableView) -> Int {
  return 1
  }

Example/Source/MessageViewModel.swift

@@ -60,16 +60,19 @@ class MessageViewModel {
  }
  }
 
- fileprivate func getUserData() {
- DispatchQueue.global(qos: .background).async { [weak self] in
+ func getUserData() {
+ DispatchQueue.global(qos: .default).async { [weak self] in
  self?.getDataFromFile(fileName: "user") { (userResponse: [User], _) in
  self?.users = userResponse
  }
  }
  }
 
- fileprivate func getDataFromFile<T>(fileName: String, completion: (_ data: [T], _ pagination: Pagination) -> ()) where T: Mappable {
- guard let jsonData = Data.dataFromJSONFile(fileName) else { return }
+ private func getDataFromFile<T>(fileName: String, completion: (_ data: [T], _ pagination: Pagination?) -> ()) where T: Mappable {
+ guard let jsonData = Data.dataFromJSONFile(fileName) else {
+ completion([], nil)
+ return
+ }
 
  do {
  let jsonObj = try JSON(data: jsonData)
@@ -79,9 +82,10 @@ class MessageViewModel {
  return
  }
 
- completion(listReponse.data, listReponse.pagination!)
+ completion(listReponse.data, listReponse.pagination)
  } catch {
  print("Error \(error)")
+ completion([], nil)
  return
  }
  }
@@ -132,7 +136,7 @@ extension MessageViewModel {
  return .single
  }
 
- fileprivate func handleDataSource(messages: [Message]) -> [Message] {
+ private func handleDataSource(messages: [Message]) -> [Message] {
  let modifiedArray = messages.map { msg -> Message in
  var m = msg
  m.isOutgoing = self.isOutgoingMessage(m)
@@ -142,15 +146,15 @@ extension MessageViewModel {
  return modifiedArray
  }
 
- fileprivate func isOutgoingMessage(_ message: Message) -> Bool {
+ private func isOutgoingMessage(_ message: Message) -> Bool {
  guard let user = currentUser else {
  return false
  }
 
  return message.sendByID == user.id
  }
 
- fileprivate func getIndexPathWillAdds(newDataSize: Int) -> [IndexPath] {
+ private func getIndexPathWillAdds(newDataSize: Int) -> [IndexPath] {
  let currentNumberMessage = messages.count
  let newNumberMessage = messages.count + newDataSize
  var indexPathWillAdds: [IndexPath] = []