Xcode swift 3 Json iteration

Question

I just started a new IOS app and I've some issue with Json (I read everything I could on this website an other, but I didn't manage to make it work properly...

I've a json file and I want to change labels with the content of it.

This is my json file:

{
    "cours": [{
        "name": "Terrain blanc",
        "nbre": "4",
        "image": "urlimage",
        "prix": "595",
        "desc": "hhhhh"
    }, {
        "name": "Terrain blanc",
        "nbre": "6",
        "image": "urlimage",
        "prix": "415",
        "desc": "hhhhh"
    }, {
        "name": "Terrain bleu",
        "nbre": "4",
        "image": "urlimage",
        "prix": "595",
        "desc": "hhhhh"
    }]
}

and this is my code:

import UIKit

class SecondViewController: UIViewController {

    @IBOutlet weak var cours1Lbl: UILabel!
    @IBOutlet weak var nbreEnfants1Lbl: UILabel!
    @IBOutlet weak var description1: UILabel!
    @IBOutlet weak var prix1Lbl: UILabel!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let url = URL(string: "http://www.boisdelacambre.be/ios/json/cours.json")
        let task = URLSession.shared.dataTask(with: url!){ (data, response, error) in
            if let content = data {
                do {
                    self.cours1Lbl.text = "test"
                    let myJson = try JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers) as AnyObject
                    let listeCours: NSArray = myJson["cours"] as! NSArray
                    let nameCours = listeCours[0] as! [String:AnyObject]
                    let nomDuCours:String = (nameCours["name"] as! String?)!
                    print(nomDuCours)
                    self.cours1Lbl.text = "\(nomDuCours)"

                } catch
                {
                    print("erreur Json")
                }
            }

        }
        task.resume()
    }
}

I can print nomDuCours but I can't change self.cours1Lbl.text (the initial value stays)

Any help will be highly appreciated...

@ÖzgürErsil if it wasn't linked well, it was crashing because of the unwrapped optional. Kreps, are you sure you're not editing the label text anywhere else? — Luca D'Alberti, Mar 21 '17 at 10:11
@KrepsLaurent : Are you able to print the values in print statement through your json? If yes then double check your outlets — Anil Kukadeja, Mar 21 '17 at 10:11
I tried executing your code. It is printing "Terrain blanc" as the output. Check your outlets. Also, avoid using NSArray in swift. Instead use [[String:AnyObject]] according to your code. — PGDev, Mar 21 '17 at 10:15
Actually, I discover that it did change, but after about one minute ?? Any possible cause ? — Kreps Laurent, Mar 21 '17 at 10:33
@KrepsLaurent Update the label value on main thread like Alavaro Roman suggested. — Nirav D, Mar 21 '17 at 10:40

Alvaro Roman · Accepted Answer · 2017-03-21T10:45:37.657

1

Try changing the label's text on the main thread like so:

DispatchQueue.main.sync
{
    self.cours1Lbl.text = "\(nomDuCours)"
}

Edit:

Also, don't forget to add 'App Transport Security Settings' to your info.plist to allow the request. If you don't, then data would be nil, and your code inside the request completion won't execute:

<key>NSAppTransportSecurity</key>
<dict>
    <key>NSAllowsArbitraryLoads</key>
    <true/>
</dict>

Keep in mind that allowing all loads can cause your app to be rejected from the App Store, but for development purposes..

edited Mar 21 '17 at 10:45

answered Mar 21 '17 at 10:13

Alvaro Roman

46
1
4

Unless the developer dispatches the call, the callback is always called from the same thread (here it looks it's the main thread) – Luca D'Alberti Mar 21 '17 at 10:14
I believe @AlavaroRoman is correct. I tested the code and you would get the new value only if you wrap the assignment to happen in the main thread. – Fahim Mar 21 '17 at 10:27
Thanks a lot you saved my life ! – Kreps Laurent Mar 21 '17 at 10:51

Xcode swift 3 Json iteration

1 Answers1