How to create a Model for dynamic keys , json parsing ,swift5 - ios

Question

I am parsing a json data and trying to create a Model but can't figure out how to achieve the title and extract properties from the json data (which I have provided), as pageids property is dynamic. Please tell me how can I create Model to extract the title property from the page using id (stored in pageids property)
link for jsonData https://en.wikipedia.org/w/api.php?exintro=&titles=canterbury%20bells&indexpageids=&format=json&pithumbsize=500&explaintext=&redirects=1&action=query&prop=extracts%7Cpageimages
I tried little a bit, below is my code but I don't think that's correct
var ID = ""
struct Document:Codable {
let batchcomplete:String
let query:Query
}
struct Query:Codable {
let normalized:[Normalized]
let pages:Pages
var pageids:[String]{
didSet{
ID = oldValue[0]
}
}
}
struct Normalized:Codable {
let from:String
let to:String // it is a name of an flower
}
struct Pages:Codable {
let id:[Pages2]
enum CodingKeys:CodingKey {
case id = "\(ID)"
}
}
struct Pages2:Codable {
let title:String // this is an official name of flower
let extract:String // this is a body
let thumbnail:Thumbnail
}
struct Thumbnail:Codable {
let source:String //this is an url for photo
}

Answer 1

The model to map your JSON will be something like this:
struct Document: Codable {
let batchcomplete: String
let query: Query
}
struct Query: Codable {
let normalized: [Normalized]
var pageids: [String]
let pages: [String: Page]
}
struct Normalized: Codable {
let from: String
let to: String
}
struct Page: Codable {
let title: String
let extract: String
let thumbnail: Thumbnail
}
struct Thumbnail: Codable {
let source: String
}
and you have access to each page using pageids array and pages dictionary:
let decoder = JSONDecoder()
do {
let decoded = try decoder.decode(Document.self, from: Data(jsonString.utf8))
decoded.query.pageids.forEach { id in
guard let page = decoded.query.pages[id] else { return }
print(page.title)
}
} catch {
print(error)
}
However I would prefer to make a small change to the model in order to make access to pages easier. That will require to customly implement the decoding of Query struct:
struct Query: Decodable {
let normalized: [Normalized]
let pages: [Page]
enum CodingKeys: String, CodingKey {
case normalized
case pageids
case pages
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
normalized = try container.decode([Normalized].self, forKey: .normalized)
let pageids = try container.decode([String].self, forKey: .pageids)
let pagesDict = try container.decode([String: Page].self, forKey: .pages)
pages = pageids.compactMap { pagesDict[$0] }
}
}
Then, access to each page would be as simple as a loop:
let decoder = JSONDecoder()
do {
let decoded = try decoder.decode(Document.self, from: Data(jsonString.utf8))
decoded.query.pages.forEach { page in
print(page.title)
}
} catch {
print(error)
}