tableView.reloadData() How to correctly reload data? - swift

Question

class ProductTableViewController: UITableViewController
{
var products = [Product]()
override func viewDidLoad() {
super.viewDidLoad()
getData()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return products.count // zero
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "ProductCell", for: indexPath) as! ProductCell
cell.userIdLabel?.text = "user id" + "$\(products[indexPath.row].userId)"
cell.idLabel?.text = "id" + "$\(products[indexPath.row].id)"
cell.titleLabel?.text = products[indexPath.row].title
cell.bodyLabel?.text = products[indexPath.row].body
return cell
}
func getData(){
let url = URL(string: "https://jsonplaceholder.typicode.com/posts")
URLSession.shared.dataTask(with:url!, completionHandler: {(data, response, error) in
guard let data = data, error == nil else { return }
do {
let json = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as! [[String:Any]]
for post in json{
let product = Product()
product.userId = post["userId"] as! Int
product.id = post["id"] as! Int
product.title = post["title"] as! String
product.body = post["body"] as! String
self.products.append(product)
}
//OperationQueue.main.addOperation({ () -> Void in self.tableView.reloadData()})
} catch let error as NSError {
print(error)
}
//HERE!!!
OperationQueue.main.addOperation({ () -> Void in self.tableView.reloadData()})
}).resume()
}
}
When my UITableViewController executed first of all will implement func tableView and he will return zero count cause getData() didn't run yet and of course second tableView who returning my Cell will not implement.
And now, I wanna see what parsed my getData() in order to do I try to reload my tableView with OperationQueue.main.addOperation({ () -> Void in self.tableView.reloadData()})but caught an error :
Thread1 :SIGABRT.
How I should correctly reload my tableView?

Answer 1

Try this
func getData(){
let url = URL(string: "https://jsonplaceholder.typicode.com/posts")
URLSession.shared.dataTask(with:url!, completionHandler: {(data, response, error) in
guard let data = data, error == nil else { return }
do {
let json = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as! [[String:Any]]
for post in json{
let product = Product()
product.userId = post["userId"] as! Int
product.id = post["id"] as! Int
product.title = post["title"] as! String
product.body = post["body"] as! String
self.products.append(product)
}
// just reload here after finish appends
self.tableView.reloadData()
} catch let error as NSError {
print(error)
}
}).resume()
}