decoding complicated JSON objects in Swift - json

Question

I'm totally new to development. Tried to find solution but they don't help me. I need do decode next JSON data:
{
"page": {
"currentPage": 1,
"batchSize": 400,
"totalItems": "23"
},
"items": [
{
"id": "b435a598-421c-4812-a3a9-773c47864558",
"firstname": "\u041d\u0410\u0422\u0410\u041b\u0406\u042f \u0412\u0406\u041a\u0422\u041e\u0420\u0406\u0412\u041d\u0410",
"lastname": "\u0413\u0423\u041d\u042c\u041a\u041e",
"placeOfWork": "\u0437\u0430\u0441\u0442\u0443\u043f\u043d\u0438\u043a \u0434\u0438\u0440\u0435\u043a\u0442\u043e\u0440\u0430-\u043d\u0430\u0447\u0430\u043b\u044c\u043d\u0438\u043a \u0432\u0456\u0434\u0434\u0456\u043b\u0443 \u0441\u043e\u0446\u0456\u0430\u043b\u044c\u043d\u043e\u0457 \u0440\u043e\u0431\u043e\u0442\u0438 ",
"position": "",
"linkPDF": "https://public.nazk.gov.ua/storage/documents/pdf/b/4/3/5/b435a598-421c-4812-a3a9-773c47864558.pdf"
},
......
]
}
I tried this code:
struct Declarant: Codable {
var id: String
var firstname: String
var lastname: String
var placeOfWork: String
var position: String
var linkPDF: String
enum CodingKeys: String, CodingKey {
case id
case firstname
case lastname
case placeOfWork
case position
case linkPDF
}
init(from decoder: Decoder) throws {
let valueContainer = try decoder.container(keyedBy: CodingKeys.self)
self.id = try valueContainer.decode(String.self, forKey: CodingKeys.id)
self.firstname = try valueContainer.decode(String.self, forKey: CodingKeys.firstname)
self.lastname = try valueContainer.decode(String.self, forKey: CodingKeys.lastname)
self.placeOfWork = try valueContainer.decode(String.self, forKey: CodingKeys.placeOfWork)
self.position = try valueContainer.decode(String.self, forKey: CodingKeys.position)
self.linkPDF = try valueContainer.decode(String.self, forKey: CodingKeys.linkPDF)
}
}
struct DeclarationInfo: Codable {
let items: [Declarant]
enum CodingKeys: String, CodingKey {
case items
}
init(from decoder: Decoder) throws {
let valueContainer = try decoder.container(keyedBy: CodingKeys.self)
self.items = [try valueContainer.decode(Declarant.self, forKey: CodingKeys.items)]
}
}
...
let dataTask = URLSession.shared.dataTask(with: url) {
(data, response, error) in
let jsonDecoder = JSONDecoder()
print("Trying to decode data...")
if let data = data, let declarationInfo = try? jsonDecoder.decode(DeclarationInfo.self, from: data) {
completion(declarationInfo)
print(declarationInfo)
} else {
print("Either no data was returned, or data was not properly decoded.")
completion(nil)
}
}
and getting
Either no data was returned, or data was not properly decoded.
Where is the mistake?

Answer 1

self.items = [try valueContainer.decode(Declarant.self, forKey: CodingKeys.items)]
Should be
self.items = try valueContainer.decode( [ Declarant ].self, forKey: CodingKeys.items )
Full code:
import UIKit
struct Declarant: Codable {
var id: String
var firstname: String
var lastname: String
var placeOfWork: String
var position: String
var linkPDF: String
}
struct DeclarationInfo: Codable {
let items: [Declarant]
}
let json = """
{ \"page\" : {
\"currentPage\" : 1
, \"batchSize\" : 400
, \"totalItems\" : "23"
}
, \"items\" : [
{ \"id\" : "b435a598-421c-4812-a3a9-773c47864558 1"
, \"firstname\" : "The first name 1"
, \"lastname\" : "The last name 1"
, \"placeOfWork\" : "The placeofWork 1"
, \"position\" : "The position 1"
, \"linkPDF\" : "https://public.nazk.gov.ua/storage/documents/pdf/b/4/3/5/b435a598-421c-4812-a3a9-773c47864558.pdf"
}
, { \"id\" : "b435a598-421c-4812-a3a9-773c47864558 2"
, \"firstname\" : "The first name 2"
, \"lastname\" : "The last name 2"
, \"placeOfWork\" : "The placeofWork 2"
, \"position\" : "The position 2"
, \"linkPDF\" : "https://public.nazk.gov.ua/storage/documents/pdf/b/4/3/5/b435a598-421c-4812-a3a9-773c47864558.pdf"
}
]
}
"""
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let jsonDecoder = JSONDecoder()
print("Trying to decode data...")
if let data = json.data(using: .utf8),
let declarationInfo = try? jsonDecoder.decode(DeclarationInfo.self, from: data) {
print(declarationInfo)
} else {
print("Either no data was returned, or data was not properly decoded.")
}
}
}
Result in console:
Trying to decode data...
DeclarationInfo(items: [Dec.Declarant(id: "b435a598-421c-4812-a3a9-773c47864558 1", firstname: "The first name
1", lastname: "The last name 1", placeOfWork: "The placeofWork 1",
position: "The position 1", linkPDF:
"https://public.nazk.gov.ua/storage/documents/pdf/b/4/3/5/b435a598-421c-4812-a3a9-773c47864558.pdf"),
Dec.Declarant(id: "b435a598-421c-4812-a3a9-773c47864558 2", firstname:
"The first name 2", lastname: "The last name 2", placeOfWork: "The
placeofWork 2", position: "The position 2", linkPDF:
"https://public.nazk.gov.ua/storage/documents/pdf/b/4/3/5/b435a598-421c-4812-a3a9-773c47864558.pdf")])