Decode JSON with variables in Swift - json

Question

I am trying to decode this type of JSON-Data in Swift
{"Total ingredients":[{"PE-LLD":"54.4 %"},{"PE-HD":"41.1 %"},{"TiO2":"4.5 %"}]}
The name and number of ingredients is variable. Therefore I am only able to decode it in this type of structure:
struct Product: Codable {
var total_ingredients: [[String: String]]?
private enum CodingKeys : String, CodingKey {
case total_ingredients = "Total ingredients"
}
}
But I would like to be able to decode it in either one dictionary: var total_ingredients: [String: String]? or my preferred choice in an array of objects: var total_ingredients: [Ingredient]?
struct Ingredient: Codable {
var name: String
var percentage: String
}
I already tried to solve my problem with an extension but it isn't working and I don't think that's the correct approach:
extension Ingredient {
init(_ ingredient: [String: String]) {
var key: String = ""
var value: String = ""
for data in ingredient {
key = data.key
value = data.value
}
self = .init(name: key, percentage: value)
}
}
Thanks in advance :)

Answer 1

You have to implement init(from decoder and map the array of dictionaries to Ingredient instances
struct Product: Decodable {
let totalIngredients: [Ingredient]
private enum CodingKeys : String, CodingKey { case totalIngredients = "Total ingredients" }
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
let ingredientData = try container.decode([[String:String]].self, forKey: .totalIngredients)
totalIngredients = ingredientData.compactMap({ dict -> Ingredient? in
guard let key = dict.keys.first, let value = dict[key] else { return nil }
return Ingredient(name: key, percentage: value)
})
}
}
struct Ingredient {
let name, percentage: String
}
let jsonString = """
{"Total ingredients":[{"PE-LLD":"54.4 %"},{"PE-HD":"41.1 %"},{"TiO2":"4.5 %"}]}
"""
let data = Data(jsonString.utf8)
do {
let result = try JSONDecoder().decode(Product.self, from: data)
print(result)
} catch {
print(error)
}
The extension is not needed.