Array from a jsonDecoder object

Question

This might be a very easy question (sorry!).

I would like to links a mySQL database to a Quiz App in Swift 4. Therefore I connected to a service.php and got the information with decodable.

How can I access this information to show in a label? Do I have to make a new Array and append the objects?

import UIKit

struct Question: Codable {

let id: String?
let frage: String?
let antwort1: String?
let antwort2: String?
let antwort3: String?
let antwort4: String?
let correct: String?
let notiz: String?
let lernsektorID: String?
let lerneinheitID: String?
let lernbereichID: String?
let schwierigkeitID: String?
let redakteur: String?
let createdAt: String?

enum CodingKeys: String, CodingKey {
    case id = "ID"
    case frage = "Frage"
    case antwort1 = "Antwort1"
    case antwort2 = "Antwort2"
    case antwort3 = "Antwort3"
    case antwort4 = "Antwort4"
    case correct = "Correct"
    case notiz = "Notiz"
    case lernsektorID = "LernsektorID"
    case lerneinheitID = "LerneinheitID"
    case lernbereichID = "LernbereichID"
    case schwierigkeitID = "SchwierigkeitID"
    case redakteur = "Redakteur"
    case createdAt = "created_at"
}
}

var fragen = [Question]()

let url = "https://redaktion.pflegonaut.de/service.php"
let urlObj = URL(string: url)

URLSession.shared.dataTask(with: urlObj!) { (data, response, error) in
do {
     self.fragen = try JSONDecoder().decode([Question].self, from: data!)
// can I use .append() here?
// maybe in a for loop?

} catch {
    print(error)
}
}.resume()

So I can use the elements like:

//
// let randomizedQuestion = fragen.frage.randomElement()
// 
// questionOutlet.text = randomizedQuestion

Thanks!

vadian · Accepted Answer · 2018-12-16 14:26:03Z

1

// NECESSARY? var QuestionBankJson: [QuestionJson] { var questionListJson = [QuestionJson]() }

No, just declare one array and name the struct simply Question

var questions = [Question]()

and assign

do {
  self.questions = try JSONDecoder().decode([Question].self, from: data!)
  print(self.questions[1].Frage!) 
} catch {
    print(error) // never print something meaningless like "we got an error"
}

Notes:

Please conform to the naming convention that variable names start with a lowercase letter.
If you are responsible for the JSON declare also the keys lowercased otherwise use CodingKeys.
Declare the struct members as much non-optional as possible.
Never print a meaningless literal string when catching Codable errors. Print always the error instance.
Use a better date string format than this arbitrary German format. UNIX time stamp, SQL date string or ISO8601 are sortable and can be even decoded to Date.

edited Dec 16, 2018 at 14:26

answered Dec 16, 2018 at 14:13

vadian

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8 Comments

Valonaut Over a year ago

Thanks! I do my very best to make the code fitting the standard format.

Valonaut Over a year ago

But how can I access the "question" Array to questionOutlet.text = question[1].Frage

vadian Over a year ago

Declare the array on the top level of the class. Then access the array by index or in a loop depending on your design. (Consider that indices in Swift are zero-based).

Valonaut Over a year ago

I am sorrry i do not get it. Can you show me how to? I declared an Array at the top, but when I print it, it shows no results. In Addition to that I used CodingKeys but it did not fit to the codable protocol.

vadian Over a year ago

Better edit your question and add the relevant code.

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