Updating array value using find object in the background is swift - arrays

Question

I'm trying to retrieve data from Parse using findObjectsInbackground and store it in an array. I've already created outside the scoop of viewDidLoad().
I managed retrieving and printing the data, but they are not stored in the array and it keeps being empty!
I used self.articalsTableView.reloadData() but unfortunately the array myArray is still empty.
Any help please, this has been confusing me for two days!
import UIKit
import Parse
class FirstViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
#IBOutlet weak var articalsTableView: UITableView!
var myArray = [PFObject]()
override func viewDidLoad() {
super.viewDidLoad()
let query = PFQuery(className: "Gateshead")
query.findObjectsInBackground {(objects, error) -> Void in
if error != nil {
print(error)
} else {
if let articals = objects {
for artical in articals {
// print (articles) THIS IS WOKING WELL
self.myArray.append(artical)
self.articalsTableView.reloadData()
}
}
}
}
}
}

Answer 1

findObjectsInback is using a background thread and you should dispatch to mainThread whenever if you want to access UIKit stuff in this case updating self.articalsTableView.
Also self.articalsTableView.reloadData() should be called at the end (not in the loop). This to prevent a race condition on self.myArray being accessed by the main-thread (to update self.articalsTableView ) and by the background-thread (to append artical)
for artical in articals {
// print (articles) THIS IS WOKING WELL
self.myArray.append(artical)
}
DispatchQueue.main.async {
self.articalsTableView.reloadData()
}