Decode json object in Swift - swift

Question

I have a json file and reading it and decode it as follows.
my json file looks like as follows, A and B represents the struct object. I wonder are there a better and effective way to decoding this type of json?
[
[
{"id": "152478", "age": "20"},{"character": "king", "isDead":"no", "canMove" :"yes"}
],
[
{"id": "887541", "age": "22"},{"character": "lion", "isDead":"no", "canMove" :"yes"}
]
]
decoding is as follows:
let url = Bundle.main.url(forResource: "mypew", withExtension: "json")!
do {
let jsonData = try Data(contentsOf: url)
// B -> json[0][0], [1][0]
// A -> json[0][1], [0][1]
response = try JSONSerialization.jsonObject(with: jsonData) as! [[[String: Any]]]
for i in 0..<response.count
{
for j in 0..<response[i].count
{
if j == 0
{
let jsonDat = (try? JSONSerialization.data(withJSONObject:response[i][j]))!
let bElement = try JSONDecoder().decode(B.self, from: jsonDat)
self.bArray.append(bElement)
}
else if j == 1
{
let jsonDatt = (try? JSONSerialization.data(withJSONObject:response[i][j]))!
let aElement = try JSONDecoder().decode(A.self, from: jsonDatt)
self.aArray.append(aElement)
}
}
}

Answer 1

First, make the two objects (let's call them A and B) conform to Decodable:
struct A: Decodable {
var id, age: String
}
struct B: Decodable {
var character, isDead, canMove: String
}
Then, if your structure for the pair of A and B is always the same, i.e. it's always [A, B], then you can decode the pair into its own object. Let's call that object ABPair:
struct ABPair: Decodable {
let a: A
let b: B
init(from decoder: Decoder) throws {
var container = try decoder.unkeyedContainer()
guard let a = try? container.decode(A.self),
let b = try? container.decode(B.self)
else {
// throw since we didn't find A first, followed by B
throw DecodingError.dataCorruptedError(in: container, debugDescription: "error")
}
self.a = a
self.b = b
}
}
And you can decode the array of pairs as follows:
let decoder = JSONDecoder()
let pairs = try? decoder.decode([ABPair].self, from: jsonData)
print(pairs[1].b.character) // lion

Answer 2

Firstly, you need to create a Codable struct for the model. Then decode the model from the data and not the JSON object. Here the code,
Model:
struct Model: Codable {
let id, age, character, isDead, canMove: String?
}
Decoding:
let url = Bundle.main.url(forResource: "mypew", withExtension: "json")!
do {
let jsonData = try Data(contentsOf: url)
let models = try JSONDecoder().decode([[Model]].self, from: jsonData)
for model in models {
print(model[0].age, model[1].canMove)
}
} catch {
print(error)
}