Refresh value in text label from JSON, with Xcode - ios

Question

I am learning Swift to develop macOS applications and I ran into a problem. I am trying to get certain data from a JSON from the internet. I have managed to get such data and put it in simple text labels in the view but when I run Xcode and get the values, if the values from the JSON get updated, I can't see it reflected in my app. I know that I must perform a function to refresh the data but what I have always found is the function to refresh the data that is in a table, not a simple text label.
Regardless of this problem, if I wanted to add a table with 3 columns (each structure has 3 data, at least) with the values from the JSON. When I run the refresh of the table, I should include in the function the function that gets the data from the internet, right? I'm a bit lost with this too.
This is what I have:
ViewController.swift
import Cocoa
class ViewController: NSViewController, NSTextFieldDelegate {
let user_items = UserItems()
#IBOutlet var item_salida: NSTextField!
override func viewDidLoad() {
super.viewDidLoad()
let struc_item = user_items.Item_Struct()
let position = struc_item.firstIndex(where: { $0.name == "Leanne Graham" })!
print(struc_item[position].state!)
item_salida.stringValue = struc_item[position].state!
} }
Struct.swift
import Foundation
import SwiftyJSON
// MARK: - Dato
struct User: Codable {
var name: String?
var username: String?
var email: String?
}
typealias Datos = [User]
class UserItems {
func Item_Struct() -> Datos {
let urlString = "https://jsonplaceholder.typicode.com/users"
var items_available: [User] = []
if let url = NSURL(string: urlString){
if let data = try? NSData(contentsOf: url as URL, options: []){
let items = try! JSONDecoder().decode([User].self, from: data as Data)
for item in items {
items_available.append(item)
}
}
}
return items_available
}
}
Thanks, a lot!

Answer 1

First of all - as you are learning Swift - please stop using snake_case variable names and also the NS.. classes NSURL and NSData.
Never load data from a remote URL with synchronous Data(contentsOf. It blocks the thread.
You need URLSession and an asynchronous completion handler.
// MARK: - Dato
struct User: Codable {
let name: String
let username: String
let email: String
}
typealias Datos = [User]
class UserItems {
func loadData(completion: #escaping (Datos) -> Void) {
let url = URL(string: "https://jsonplaceholder.typicode.com/users")!
URLSession.shared.dataTask(with: url) { data, _, error in
if let error = error { print(error); return }
do {
let items = try JSONDecoder().decode([User].self, from: data!)
completion(items)
} catch {
print(error)
}
}.resume()
}
}
And use it in the controller
class ViewController: NSViewController, NSTextFieldDelegate {
#IBOutlet var itemSalida: NSTextField!
let userItems = UserItems()
override func viewDidLoad() {
super.viewDidLoad()
userItems.loadData { users in
if let position = users.firstIndex(where: { $0.name == "Leanne Graham" }) {
DispatchQueue.main.async {
print(users[position].username)
self.itemSalida.stringValue = users[position].username
}
}
}
}
}
And forget SwiftyJSON. It's not needed anymore in favor of Codable.