Struct Init with JSON and flatMap - json

Question

I'm having a problem with the following code. I'm downloading a list of actors in JSON and I want to populate Struct Actor with the received data. Everything works great until I try to flatMap on the received data and try to initialize the struct Actor. When I try to compile the code i get the error: Cannot assign value of type '()' to type [Actor]. The error corresponds to a line in viewDidLoad actorsList = downloadActors() Would anybody have any recommendation who to solve this?
import UIKit
func downloadActors() {
var request = URLRequest(url: URL(string: "url...")!)
request.httpMethod = "POST"
let postString = "actorGroup=\("Superhero")"
request.httpBody = postString.data(using: .utf8)
let task = URLSession.shared.dataTask(with: request) { data, response, error in
DispatchQueue.main.async {
guard let data = data, error == nil else {
print("error=\(error)")
return
}
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode != 200 {
print("error : statusCode should be 200 but is \(httpStatus.statusCode)")
print("response = \(response)")
}
if let httpStatus = response as? HTTPURLResponse, httpStatus.statusCode == 200 {
do {
let json = try JSONSerialization.jsonObject(with: data, options: JSONSerialization.ReadingOptions.mutableContainers) as? [String: AnyObject]
guard let actorsJSON = json?["response"] as? [[String : AnyObject]] else {
return
}
} catch {
print("catch error")
}
}
}
}
task.resume()
}
func loadActors() -> [Actor] {
if let actors = actorsJSON as? [[String : AnyObject]] {
return actors.flatMap(Actor.init)
}
}
let actorsArray = loadActors()
class MasterViewController: UITableViewController {
var actorsList = [Actor]()
var detailViewController: DetailViewController? = nil
var objects = [Any]()
override func viewDidLoad() {
super.viewDidLoad()
actorsList = downloadActors()
print(actorsList)
Struct Actors is as follows:
struct Job {
let actorGroup: String
let actorName: String
}
extension Actor: JSONDecodable {
init?(JSON: [String : AnyObject]) {
guard let actorGroup = JSON["actorGroup"] as? String, let actorName = JSON["actorName"] as? String else {
return nil
}
self. actorGroup = actorGroup
self. actorName = actorName
}
}

Answer 1

let listActors = actorsJSON as? [[String : AnyObject]] {
Should be:
if let listActors = actorsJSON as? [[String : AnyObject]] {
Edit: For more info I'd like to add Vadian's comment:
Very confusing code. What does the function in the middle of the do block? Why do you type-check actorsJSON twice? The computed property is let listActors... which should be probably an optional binding (if let ... ). Further .mutableContainers is completely nonsense in Swift. And finally a JSON dictionary is [String:Any] in Swift 3.