How to reload a view-controller after data has been fetched from a network request? - ios

Question

I have a problem and can't seem to fix it after looking at tutorials online and other SO questions with a similar problem, which leaves me to think I've done something wrong/bad practice related in my code.
I have 2 table view controllers.
The first TableViewController is populated from a database, all this works fine. When I click one of the cells it segues to a second TableViewController which also should be populated from a database (depending on what you select in the first VC).
Currently if I click a cell in TVC1 it goes to TVC2 and it's empty, then it I click back within my navigation controller and select something else, it goes back to TVC2 and shows me my first selection. This indicates that TVC2 is being loaded before the network has returned its data from the database.... so, I tried using tableView.reloadData() in various places like viewDidLoad and viewDidAppear, but i just can't seem to get it to work.
Below is both TVC's. I've stuck with MVC design pattern and haven't included the model and severConnection code for each TVC because I don't want to over complicate the post, however if you'd like to see either I will update.
Thanks in advance for any help.
TableViewController1
class MenuTypeTableViewController: UITableViewController, MenuTypeServerProtocol {
//Properties
var cellItems: NSArray = NSArray()
var selectedItem = String()
override func viewDidLoad() {
super.viewDidLoad()
let menuTypeServer = MenuTypeServer()
menuTypeServer.delegate = self
menuTypeServer.downloadItems()
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cellIdentifier: String = "cellType"
let myCell: UITableViewCell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier)!
let item: MenuTypeModel = cellItems[indexPath.row] as! MenuTypeModel
myCell.textLabel?.text = item.type
return myCell
}
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
let selectedCell = tableView.cellForRow(at: indexPath)
selectedItem = (selectedCell?.textLabel?.text)!
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "typeItems" {
let destinationVC = segue.destination as? TypeItemsTableViewController
destinationVC?.selectedItem = self.selectedItem
}
}
}
TableViewController2:
class TypeItemsTableViewController: UITableViewController, TypeItemsServerProtocol {
//Properties
var cellItems: NSArray = NSArray()
var selectedItem: String = String()
let typeItemsServer = TypeItemsServer()
override func viewDidLoad() {
super.viewDidLoad()
typeItemsServer.delegate = self
self.typeItemsServer.foodType = self.selectedItem
self.typeItemsServer.downloadItems()
self.tableView.reloadData()
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return cellItems.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cellIdentifier: String = "cellTypeItem"
let myCell: UITableViewCell = tableView.dequeueReusableCell(withIdentifier: cellIdentifier)!
let item: TypeItemsModel = cellItems[indexPath.row] as! TypeItemsModel
myCell.textLabel?.text = item.name!
return myCell
}
}

Answer 1

Try adding this to TypeItemsTableViewController
override func viewDidLoad() {
super.viewDidLoad()
cellItems = NSArray()//make sure you have the empty array at the start
typeItemsServer.delegate = self
self.typeItemsServer.foodType = self.selectedItem
self.typeItemsServer.downloadItems()
self.tableView.reloadData()
}
and
override func viewDidDisappear(_ animated: Bool) {
super.viewDidDisappear(animated)
typeItemsServer.delegate = nil
}
Add this at the top
var cellItems: NSArray = NSArray() {
didSet {
tableview.reloadData()
}
}
Now you can remove other tableview.reloadData() calls since it will automatically be called once cellItems are set...

Answer 2

I think you have a timing problem. You're reloading right after your async data call. You reload but your data isn't in place at that time. Try using functions with escaping or use "didSet" on your data like:
var dataArray: [type] {
didSet {
tableview.reloadData()
}
}