How do I decode JSON(JSON Web Token) in Swift 4? - ios

Question

How do I decode this json in Swift 4, with decoder?
I want to be able to get the "token" by itself, so I can store it in the Keychain.
{
"success":true,
"token":"***"
,
"user": {
"id": "59f0ec6d5479390345980cc8",
"username": "john",
"email": "john#gmail.com"
}
}
I have tried this, but it doesn't print anything.
let session = URLSession.shared
let task = session.dataTask(with: request) { (data, _, _) in
guard let data = data else { return }
do {
let jsonwt = try JSONDecoder().decode(JWT.self, from: data)
print(jsonwt.token)
} catch {}
}
task.resume()
}
I can put this after the catch, but that gets the whole json, and I don't want that.
print(String(data: data, encoding: .utf8)!)
Here are the structures. I think this is where the problem lies.
struct User: Decodable {
let id: String
let username: String
let email: String
}
struct JWT: Decodable {
let success: String
let token: String
let user: User
}

Answer 1

Works like this:
struct User : Codable
{ var id : String
}
struct JWT : Codable
{ var success : Bool
var token : String
var user :User
}
let json = """
{ \"success\" : true,
\"token\" : \"***\",
\"user\":
{ \"id\": \"59f0ec6d5479390345980cc8\",
\"username\": \"john\",
\"email\": \"john#gmail.com\"
}
}
"""
let decoder = JSONDecoder()
let jwt = try decoder.decode(JWT.self, from: json.data(using: .utf8)!)
print ("token: \(jwt.token)")

Answer 2

Here's some playground code that demonstrates the code for parsing JSON in Swift:
//: Playground - noun: a place where people can play
import UIKit
import XCTest
import PlaygroundSupport
let json = """
{
"success":true,
"token":"***"
,
"user": {
"id": "59f0ec6d5479390345980cc8",
"username": "john",
"email": "john#gmail.com"
}
}
""".data(using: .utf8)!
do {
if let data = try JSONSerialization.jsonObject(with: json, options: .allowFragments) as? [String:Any], let token = data["token"] {
print("token is \(token)")
}
} catch _ {
print("Failed to decode JSON")
}