Extracted inner object parsing JSON example for Star Wars API - http://swapi.co/api/starships/?format=json

parseStarshipsRefactor.swift

import Foundation

/// http://swapi.co/api/starships/?format=json With "'s escaped.
let starshipsJSON = "{\"count\":36,\"next\":\"http://swapi.co/api/starships/?format=json&page=2\",\"previous\":null,\"results\":[{\"name\":\"Sentinel-class landing craft\",\"model\":\"Sentinel-class landing craft\",\"manufacturer\":\"Sienar Fleet Systems, Cyngus Spaceworks\",\"cost_in_credits\":\"240000\",\"length\":\"38\",\"max_atmosphering_speed\":\"1000\",\"crew\":\"5\",\"passengers\":\"75\",\"cargo_capacity\":\"180000\",\"consumables\":\"1 month\",\"hyperdrive_rating\":\"1.0\",\"MGLT\":\"70\",\"starship_class\":\"landing craft\",\"pilots\":[],\"films\":[\"http://swapi.co/api/films/1/\"],\"created\":\"2014-12-10T15:48:00.586000Z\",\"edited\":\"2014-12-22T17:35:44.431407Z\",\"url\":\"http://swapi.co/api/starships/5/\"},{\"name\":\"Death Star\",\"model\":\"DS-1 Orbital Battle Station\",\"manufacturer\":\"Imperial Department of Military Research, Sienar Fleet Systems\",\"cost_in_credits\":\"1000000000000\",\"length\":\"120000\",\"max_atmosphering_speed\":\"n/a\",\"crew\":\"342953\",\"passengers\":\"843342\",\"cargo_capacity\":\"1000000000000\",\"consumables\":\"3 years\",\"hyperdrive_rating\":\"4.0\",\"MGLT\":\"10\",\"starship_class\":\"Deep Space Mobile Battlestation\",\"pilots\":[],\"films\":[\"http://swapi.co/api/films/1/\"],\"created\":\"2014-12-10T16:36:50.509000Z\",\"edited\":\"2014-12-22T17:35:44.452589Z\",\"url\":\"http://swapi.co/api/starships/9/\"},{\"name\":\"Millennium Falcon\",\"model\":\"YT-1300 light freighter\",\"manufacturer\":\"Corellian Engineering Corporation\",\"cost_in_credits\":\"100000\",\"length\":\"34.37\",\"max_atmosphering_speed\":\"1050\",\"crew\":\"4\",\"passengers\":\"6\",\"cargo_capacity\":\"100000\",\"consumables\":\"2 months\",\"hyperdrive_rating\":\"0.5\",\"MGLT\":\"75\",\"starship_class\":\"Light freighter\",\"pilots\":[\"http://swapi.co/api/people/13/\",\"http://swapi.co/api/people/14/\",\"http://swapi.co/api/people/25/\",\"http://swapi.co/api/people/31/\"],\"films\":[\"http://swapi.co/api/films/1/\",\"http://swapi.co/api/films/2/\",\"http://swapi.co/api/films/3/\"],\"created\":\"2014-12-10T16:59:45.094000Z\",\"edited\":\"2014-12-22T17:35:44.464156Z\",\"url\":\"http://swapi.co/api/starships/10/\"},{\"name\":\"Y-wing\",\"model\":\"BTL Y-wing\",\"manufacturer\":\"Koensayr Manufacturing\",\"cost_in_credits\":\"134999\",\"length\":\"14\",\"max_atmosphering_speed\":\"1000km\",\"crew\":\"2\",\"passengers\":\"0\",\"cargo_capacity\":\"110\",\"consumables\":\"1 week\",\"hyperdrive_rating\":\"1.0\",\"MGLT\":\"80\",\"starship_class\":\"assault starfighter\",\"pilots\":[],\"films\":[\"http://swapi.co/api/films/1/\",\"http://swapi.co/api/films/2/\",\"http://swapi.co/api/films/3/\"],\"created\":\"2014-12-12T11:00:39.817000Z\",\"edited\":\"2014-12-22T17:35:44.479706Z\",\"url\":\"http://swapi.co/api/starships/11/\"},{\"name\":\"X-wing\",\"model\":\"T-65 X-wing\",\"manufacturer\":\"Incom Corporation\",\"cost_in_credits\":\"149999\",\"length\":\"12.5\",\"max_atmosphering_speed\":\"1050\",\"crew\":\"1\",\"passengers\":\"0\",\"cargo_capacity\":\"110\",\"consumables\":\"1 week\",\"hyperdrive_rating\":\"1.0\",\"MGLT\":\"100\",\"starship_class\":\"Starfighter\",\"pilots\":[\"http://swapi.co/api/people/1/\",\"http://swapi.co/api/people/9/\",\"http://swapi.co/api/people/18/\",\"http://swapi.co/api/people/19/\"],\"films\":[\"http://swapi.co/api/films/1/\",\"http://swapi.co/api/films/2/\",\"http://swapi.co/api/films/3/\"],\"created\":\"2014-12-12T11:19:05.340000Z\",\"edited\":\"2014-12-22T17:35:44.491233Z\",\"url\":\"http://swapi.co/api/starships/12/\"},{\"name\":\"TIE Advanced x1\",\"model\":\"Twin Ion Engine Advanced x1\",\"manufacturer\":\"Sienar Fleet Systems\",\"cost_in_credits\":\"unknown\",\"length\":\"9.2\",\"max_atmosphering_speed\":\"1200\",\"crew\":\"1\",\"passengers\":\"0\",\"cargo_capacity\":\"150\",\"consumables\":\"5 days\",\"hyperdrive_rating\":\"1.0\",\"MGLT\":\"105\",\"starship_class\":\"Starfighter\",\"pilots\":[\"http://swapi.co/api/people/4/\"],\"films\":[\"http://swapi.co/api/films/1/\"],\"created\":\"2014-12-12T11:21:32.991000Z\",\"edited\":\"2014-12-22T17:35:44.549047Z\",\"url\":\"http://swapi.co/api/starships/13/\"},{\"name\":\"Executor\",\"model\":\"Executor-class star dreadnought\",\"manufacturer\":\"Kuat Drive Yards, Fondor Shipyards\",\"cost_in_credits\":\"1143350000\",\"length\":\"19,000\",\"max_atmosphering_speed\":\"n/a\",\"crew\":\"279144\",\"passengers\":\"38000\",\"cargo_capacity\":\"250000000\",\"consumables\":\"6 years\",\"hyperdrive_rating\":\"2.0\",\"MGLT\":\"40\",\"starship_class\":\"Star dreadnought\",\"pilots\":[],\"films\":[\"http://swapi.co/api/films/2/\",\"http://swapi.co/api/films/3/\"],\"created\":\"2014-12-15T12:31:42.547000Z\",\"edited\":\"2014-12-22T17:35:44.638231Z\",\"url\":\"http://swapi.co/api/starships/15/\"},{\"name\":\"Slave 1\",\"model\":\"Firespray-31-class patrol and attack\",\"manufacturer\":\"Kuat Systems Engineering\",\"cost_in_credits\":\"unknown\",\"length\":\"21.5\",\"max_atmosphering_speed\":\"1000\",\"crew\":\"1\",\"passengers\":\"6\",\"cargo_capacity\":\"70000\",\"consumables\":\"1 month\",\"hyperdrive_rating\":\"3.0\",\"MGLT\":\"70\",\"starship_class\":\"Patrol craft\",\"pilots\":[\"http://swapi.co/api/people/22/\"],\"films\":[\"http://swapi.co/api/films/2/\",\"http://swapi.co/api/films/5/\"],\"created\":\"2014-12-15T13:00:56.332000Z\",\"edited\":\"2014-12-22T17:35:44.716273Z\",\"url\":\"http://swapi.co/api/starships/21/\"},{\"name\":\"Imperial shuttle\",\"model\":\"Lambda-class T-4a shuttle\",\"manufacturer\":\"Sienar Fleet Systems\",\"cost_in_credits\":\"240000\",\"length\":\"20\",\"max_atmosphering_speed\":\"850\",\"crew\":\"6\",\"passengers\":\"20\",\"cargo_capacity\":\"80000\",\"consumables\":\"2 months\",\"hyperdrive_rating\":\"1.0\",\"MGLT\":\"50\",\"starship_class\":\"Armed government transport\",\"pilots\":[\"http://swapi.co/api/people/1/\",\"http://swapi.co/api/people/13/\",\"http://swapi.co/api/people/14/\"],\"films\":[\"http://swapi.co/api/films/2/\",\"http://swapi.co/api/films/3/\"],\"created\":\"2014-12-15T13:04:47.235000Z\",\"edited\":\"2014-12-22T17:35:44.795405Z\",\"url\":\"http://swapi.co/api/starships/22/\"},{\"name\":\"EF76 Nebulon-B escort frigate\",\"model\":\"EF76 Nebulon-B escort frigate\",\"manufacturer\":\"Kuat Drive Yards\",\"cost_in_credits\":\"8500000\",\"length\":\"300\",\"max_atmosphering_speed\":\"800\",\"crew\":\"854\",\"passengers\":\"75\",\"cargo_capacity\":\"6000000\",\"consumables\":\"2 years\",\"hyperdrive_rating\":\"2.0\",\"MGLT\":\"40\",\"starship_class\":\"Escort ship\",\"pilots\":[],\"films\":[\"http://swapi.co/api/films/2/\",\"http://swapi.co/api/films/3/\"],\"created\":\"2014-12-15T13:06:30.813000Z\",\"edited\":\"2014-12-22T17:35:44.848329Z\",\"url\":\"http://swapi.co/api/starships/23/\"}]}"

var error:NSError?
let spaceShipsJSON = starshipsJSON.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false) ?? NSData()

typealias JSONDict = [String:AnyObject]

let parsed = NSJSONSerialization.JSONObjectWithData(spaceShipsJSON, options: NSJSONReadingOptions.allZeros, error: &error) as? JSONDict

struct Starship : Printable {
    var model:String
    var shipClass:String
    var length:NSDecimalNumber
    var description:String { get {
            return "A \(model) is a \(shipClass) class starship and is \(length)m long."
        }
    }
}

extension Starship {
    init?(dict:JSONDict) {
        if let model = dict["model"] as? String {
            self.model = model
        } else { return nil }
        if let shipClass = dict["starship_class"] as? String {
            self.shipClass = shipClass
        } else { return nil }
        if let lengthString = dict["length"] as? String {
            let length = NSDecimalNumber(string: lengthString, locale: NSLocale(localeIdentifier: "en_US_POSIX"))
            if length.isEqualToNumber(NSDecimalNumber.notANumber()) {
                return nil
            }
            self.length = length
        } else {
            return nil
        }
    }
}

if let results = parsed?["results"] as? [JSONDict] {

    let starshipsOpts = results.map {
        Starship(dict: $0)
    }
    
    // Remove nil items. Could be included in added nonnilmap variant of map easily written with generics
    let starships = starshipsOpts.filter { $0 != nil }.map { $0! }
    
    // Abuse map for side effect
    starships.map { println($0) }
}