Parsing JSON to a struct with SwiftyJSON

I have a simple struct to handle the data parsing from the SwiftyJSON

struct Threads{
    var threads:[ThreadDetail]
}

struct ThreadDetail {
    var title:String
    var username:String
    var prefix_id:Int
}

Here's a sample of the API response

{
    "threads": [
        {
            "first_post_id": 258535,
            "prefix_id": 1,
            "thread_id": 50204,
            "title": "Testing board title",
            "user_id": 20959,
            "username": "test",
            "view_count": 247,
        }

Now here's the part where I couldn't figure out how

        Alamofire.request(url, method: .get, headers: headers).validate().responseJSON { response in
            switch response.result {
            case .success(let value):
                let json = JSON(value)
                for item in json["threads"].arrayValue {

                    //how should it be written here?

                }
            case .failure(let error):
                print(error)
            }
        }
    }
}

Declare your models and conform them Codable.

struct Response: Codable {
    let threads: [Thread]
}

// MARK: - Thread
struct Thread: Codable {
    let firstPostID, prefixID, threadID: Int
    let title: String
    let userID: Int
    let username: String
    let viewCount: Int

    enum CodingKeys: String, CodingKey {
        case firstPostID = "first_post_id"
        case prefixID = "prefix_id"
        case threadID = "thread_id"
        case title
        case userID = "user_id"
        case username
        case viewCount = "view_count"
    }
}

After that, convert your data to model by using JSONDecoder

  Alamofire.request(urlString).response {
            response in
            guard let data = response.data else { return }
            do {
                let decoder = JSONDecoder()
                let threadsWrapper = try decoder.decode(Response.self, from: data)
            } catch let error {
                print(error)
            }

Use this website to convert your JSON to Codable https://app.quicktype.io/