Swift 3, how to parse first and show it on next TableViewController - ios

Question

I am really new to developing iOS apps. So I also apologize in advance if my coding is not close to being optimal or good written...
I am trying to create fairly simple app only for showing retrieving and showing data, but I hit a bump which I am trying to solve it for past few days, but I need help...
So the whole functionality of the app is like this: when opened(displying viewcontroller with textfield and button), user should enter username and push button. After button is pushed app should then do 2 things in next order:
combine certain URL address with entered username, retrieve data
(what kind of data, depends on given username - I gave few examples
on the bottom of that post) and pass them to next
tableviewcontroller
display tableviewcontroller and show parsed data.
But, this does not happen, what I noticed is, that my app opens new tableviewconotrller first, and after tableviewcontroller is open, it parses data, which causes that my table has no data (but I can see that data has been parsed, using print())
I am using Swift 3.
ViewController with textfield and button for "login":
import UIKit
class ViewController: UIViewController {
var zavodi = [[String]]()
#IBOutlet weak var uporabnik: UITextField!
#IBAction func vstop(_ sender: Any) {
self.parse { (completed) in
if (completed){
let zavodiView = self.storyboard?.instantiateViewController(withIdentifier: "zavodiController") as! ZavodiController
zavodiView.niz = self.uporabnik.text!
zavodiView.zavodi = self.zavodi
self.navigationController?.pushViewController(zavodiView, animated: true)
}
}
}
override func viewDidLoad() {
super.viewDidLoad()
self.title="Vstop"
}
func parse( completion: #escaping (_ completed: Bool)-> () ){
let uporabnikIme = uporabnik.text!
//parsing
let shramba = UserDefaults.standard
let zavodiUrl = "https://oaza.rrc.si/eZaporiMobi/kapStSta/read?pUporabniskoIme="+uporabnikIme;
var zavodiRequest = URLRequest(url: URL(string: zavodiUrl)!)
zavodiRequest.httpMethod = "GET"
let configuration = URLSessionConfiguration.default
let session = URLSession(configuration: configuration, delegate: nil, delegateQueue: OperationQueue.main)
let task = session.dataTask(with: zavodiRequest) { (data, response, error) in
if (error != nil) {
print("Error")
}
else {
var zavodiTemp = [Zavod]()
do {
let fetchedData = try JSONSerialization.jsonObject(with: data!) as! NSArray
//print(fetchedData)
zavodiTemp.removeAll()
for najdenZavod in fetchedData {
let vsakZavod = najdenZavod as! [String : Any]
let zavodId = vsakZavod["zaiId"] as! Int
let naziv = vsakZavod["kratekNaziv"] as! String
let ureditev = vsakZavod["ureditev"] as! Int
let zasedenost = vsakZavod["zasedenost"] as! String
let kapaciteta = vsakZavod["kapaciteta"] as! Int
let stStanje = vsakZavod["stStanje"] as! Int
let naBegu = vsakZavod["naBegu"] as! Int
let prekinitev = vsakZavod["prekinitev"] as! Int
zavodiTemp.append(Zavod(zavodId: zavodId, naziv: naziv, ureditev: ureditev, zasedenost: zasedenost,kapaciteta: kapaciteta, stStanje: stStanje, naBegu: naBegu, prekinitev: prekinitev))
}
zavodiTemp = zavodiTemp.sorted(by: {$0.ureditev < $1.ureditev})
self.zavodi.removeAll()
for e in zavodiTemp {
var temp = [String]()
temp.append(String(e.zavodId)) //0
temp.append(e.naziv) //1
temp.append(String(e.ureditev)) //2
temp.append(e.zasedenost) //3
temp.append(String(e.kapaciteta)) //4
temp.append(String(e.stStanje)) //5
temp.append(String(e.naBegu)) //6
temp.append(String(e.prekinitev)) //7
self.zavodi.append(temp)
}
let steviloZavodov = self.zavodi.count
shramba.set(self.zavodi, forKey:"zavodi")
shramba.set(steviloZavodov, forKey:"steviloZavodov")
var s = [[String]]()
s = shramba.array(forKey: "zavodi") as! [[String]]
for e in s{
print(e[2]+" "+e[1])
}
}
catch {
print()
}
}
}
task.resume()
completion(true)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
class Zavod {
var zavodId : Int
var naziv : String
var ureditev : Int
var zasedenost : String
var kapaciteta : Int
var stStanje : Int
var naBegu : Int
var prekinitev : Int
init(zavodId : Int, naziv : String, ureditev : Int, zasedenost : String, kapaciteta : Int, stStanje : Int, naBegu : Int, prekinitev : Int) {
self.zavodId = zavodId
self.naziv = naziv
self.ureditev = ureditev
self.zasedenost = zasedenost
self.kapaciteta = kapaciteta
self.stStanje = stStanje
self.naBegu = naBegu
self.prekinitev = prekinitev
}
}
}
TableViewController where should parsed data be displayed:
import UIKit
class ZavodiController: UITableViewController {
var niz = ""
var zavodi = [[String]]()
override func viewDidLoad() {
super.viewDidLoad()
print(niz)
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
}
override func numberOfSections(in tableView: UITableView) -> Int {
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
print("število zavodov"+String(self.zavodi.count))
return self.zavodi.count
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "zavodCelica", for: indexPath) as! ZavodCelica
cell.nazivZavoda.text = self.zavodi[indexPath.row][1]
cell.kapaciteta.text = self.zavodi[indexPath.row][4]
cell.zasedenost.text = self.zavodi[indexPath.row][3]
cell.stStanje.text = self.zavodi[indexPath.row][5]
cell.naBegu.text = self.zavodi[indexPath.row][6]
cell.prekinitev.text = self.zavodi[indexPath.row][7]
return cell
}
}
I also tried to use UserDefaults, but it just seems that tableviewcontroller just simply gets loaded before actual parsing is done.
For usernames, you can use:
-"manj", returns 1 record
-"mref", returns 3 records
-"mmli", returns 14 records
I would really appreciate any help.

Answer 1

There can be a lot of ways to achieve this. Reloading the table is also a fix. But to be very accurate with the data your should wait for the function completion before moving to the next screen. Look at the code
func parse()( completion: #escaping (_ completed: Bool)-> () ){
// parse logic goes in here
// after the processing finishes return true like following
completion(true) // you can also have logic to return failures.
}
This will be called like
self.parse { (completed) in
if (completed){
let zavodiView = storyboard?.instantiateViewController(withIdentifier: "zavodiController") as! ZavodiController
zavodiView.niz = uporabnik.text!
zavodiView.zavodi = self.zavodi
navigationController?.pushViewController(zavodiView, animated: true)
}
}

Answer 2

Afetr appending data to the table array add this
DispatchQueue.main.async {
self.tableview.reloadData()
}