Swift 4 : Decode array - arrays

Question

I want to easily decode a JSON file with Decode protocol from Swift 4 on Xcode 9. This my question :
How to decode à JSON like this:
[
{
"name": "My first Catalog",
"order": 0,
"products": [
{
"product": {
"title": "product title",
"reference": "ref"
}
}
]
}
]
I try this but it's doesn't work
fileprivate struct Catalog: Codable {
var name: String
var order: Int
var product: [Product]
}
fileprivate struct Product: Codable {
var title: String
var reference: String
}
...
// JSON Decoder
do {
let jsonData = try Data(contentsOf: URL(fileURLWithPath: filePath), options: .alwaysMapped)
let jsonDecoder = JSONDecoder()
let jsonCatalogs = try? jsonDecoder.decode(Array<Catalog>.self,
from: jsonData)
return jsonCatalogs
} catch {
print ("error")
return nil
}
I don't know why it doesn't work in Swift 4 with Xcode 9. Thank for your help ;-)

Answer 1

actually the thing is that your structs are wrong,
fileprivate struct Catalog: Codable {
var name: String
var order: Int
var products: [Products] // this key is wrong in your question, it should be products instead of product
}
//this particular structure was missing as your products is having a dictionary and in that dictionary you are having product at key product
fileprivate struct Products: Codable {
var product: Product
}
fileprivate struct Product: Codable {
var title: String
var reference: String
}
now you can check your fucntion and also you can easily debug it using try catch with error handlings
...
// JSON Decoder
do {
let jsonData = try Data(contentsOf: URL(fileURLWithPath:filePath), options: .alwaysMapped)
let jsonDecoder = JSONDecoder()
let jsonCatalogs = try? jsonDecoder.decode(Array<Catalog>.self,from: jsonData)
print(jsonCatalogs)
return jsonCatalogs
} catch let error {
print ("error -> \(error)") // this will always give you the exact reason for which you are getting error
return nil
}

Answer 2

Try this solution according to your JSON and i have worked with Decoder in swift 4 with xcode 9.4.
struct Catalog : Decodable {
let name : String?
let order : Int?
let productArray : [Products]? // this is products array.
}
struct Products : Decodable {
let productDict : Product? // this is product dictionary
}
struct Product : Decodable {
let title : String?
let reference : String?
}
var catalogArray = [Catalog]() // Declaration
// JSON Decoder
do {
let jsonData = try Data(contentsOf: URL(fileURLWithPath:filePath), options: .alwaysMapped)
let jsonDecoder = JSONDecoder()
let jsonCatalogs = try? jsonDecoder.decode(Catalog.self,from: jsonData)
return jsonCatalogs
} catch let error {
print ("error -> \(error)") // this will always give you the exact reason for which you are getting error
return nil
}
*