How to reload data in UITableView when popping view controller - swift

Question

If I have two ViewControllers one which contains a UITableView and another which updates data in the tableView. How would I reload the table data once I pop of the viewController and go back to the view with the tableView?
I already tried using viewDidAppear

Answer 1

You could use viewWillAppear just like Rajesh suggested:
override func viewWillAppear(_ animated: Bool) {
tableView.reloadData()
}
Or you could use a callback function to pass data and reload view controller 1's tableview.
In ViewController 2, define your callback function:
// Callback function
var callbackResult: ((data) -> ())?
And call it before going back to ViewController 1:
callbackResult?(data)
self.navigationController?.popViewController(animated: true)
In ViewController 1, use the callback function's closure to collect the result and reload your tableView. This can happen inside prepareForSegue, for example:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "goToViewController2" {
let destinationVC = segue.destination as! ViewController2
// Set any variable in ViewController2
destinationVC.callbackResult = { result in
// assign passing data etc..
self.tableView.reloadData()
}
}
}

Answer 2

You may try doing something like this:
class TableViewController: UITableViewController {
func showUpdatingViewController() {
let vc = UpdatingViewController()
vc.onUpdate = { [weak self] in
self?.tableView.reloadData()
}
navigationController?.pushViewController(vc, animated: true)
}
}
class UpdatingViewController: UIViewController {
var onUpdate: (() -> Void)?
func updatesFinished() {
onUpdate?()
dismiss(animated: true, completion: nil)
}
}

Answer 3

I was having similar issue and using viewWillAppear or viewDidAppear did not help me to reload the tableview.
I solved my situation by putting the reloadData() call within the unwindSegue
#IBAction func unwindToVCSetupDataScreen(_ unwindSegue: UIStoryboardSegue) {
/// Nothing is actually needed here
/// https://www.youtube.com/watch?v=WaSlHXNah7E #6:25
/// CTRL-Drag from Back button to the "exit" square at the very top of VC
tableView.reloadData()
}