How to reload tableview from another view controller in swift

I find the segue approach more elegant.

Let's say that we have ViewControllerA and a ViewControllerB. We are at ViewControllerB and we want from ViewControllerB to jump straight back to ViewControllerA and update the table view in ViewControllerA.

In ViewControllerA add the following action in your ViewController class:

@IBAction func unwindToViewControllerA(segue: UIStoryboardSegue) {
    DispatchQueue.global(qos: .userInitiated).async {
        DispatchQueue.main.async {
            self.tableView.reloadData()
        }
    }
}

Yes, this code goes in the ViewController of the ViewController you want to go back to!

Now, you need to create an exit segue from the ViewControllerB's storyboard (StoryboardB). Go ahead and open StoryboardB and select the storyboard. Hold CTRL down and drag to exit as follows:

You will be given a list of segues to choose from including the one we just created:

You should now have a segue, click on it:

Go in the inspector and set a unique id:

In the ViewControllerB at the point where you want to dismiss and return back to ViewControllerA, do the following (with the id we set in the inspector previously):

self.performSegue(withIdentifier: "yourIdHere", sender: self)

Now, whenever you use the segue to return back to ViewControllerA, the ViewControllerA will update the TableView straightaway.

Swift 3 version code: In your first view controller:

override func viewDidLoad() {
        super.viewDidLoad()
        NotificationCenter.default.addObserver(self, selector: #selector(loadList), name: NSNotification.Name(rawValue: "load"), object: nil)
    }

func loadList(){
        //load data here
        self.tableView.reloadData()
    }

In your second view controller:

NotificationCenter.default.post(name: NSNotification.Name(rawValue: "load"), object: nil)

You can do this:

In your tableView Controller:

override func viewDidLoad() {
    super.viewDidLoad()
    NotificationCenter.default.addObserver(self, selector: #selector(loadList), name: NSNotification.Name(rawValue: "load"), object: nil)
}
 
@objc func loadList(notification: NSNotification){
    //load data here
    self.tableView.reloadData()
}

Then in the other ViewController :

NotificationCenter.default.post(name: NSNotification.Name(rawValue: "load"), object: nil)