Alexander is an extremely simple JSON helper written in Swift. It brings type safety and Foundation helpers to the cumbersome task of JSON unpacking.

github "hodinkee/alexander"

pod 'Alexander'

Make a new DecoderType that can unpack your object.

struct User { var ID: String var name: String var email: String } struct UserDecoder: DecoderType { typealias Value = User static func decode(JSON: Alexander.JSON) -> Value? { guard let ID = JSON["id"]?.stringValue, let name = JSON["name"]?.stringValue, let email = JSON["email"]?.stringValue else { return nil } return User(ID: ID, name: name, email: email) } }

Now you can do let author = JSON["user"]?.decode(UserDecoder) to get a single user, or let users = JSON["users"]?.decodeArray(UserDecoder) to get an array of users.

You can make DecodableTypes for all kinds of things.

struct SizeDecoder { typealias Value = CGSize static func decode(JSON: Alexander.JSON) -> Value? { guard let width = JSON["width"]?.doubleValue, let height = JSON["height"]?.doubleValue else { return nil } return CGSize(width: width, height: height) } }

Alexander ships with a handful of decoders for common types:

• DateTimeIntervalSince1970Decoder
• DateTimeIntervalSinceReferenceDateDecoder
• URLDecoder
• RawRepresentableDecoder

Most of Alexander's power comes from its two subscript operators: subscript[key: String] -> JSON? and subscript[index: Int] -> JSON?. These operators allow you to unpack nested objects without having to refer to each intermediate step by hand. Something like let nextCursor = JSON["meta"]?["pagination"]?["next_cursor"]?.stringValue is a single line of code.

You can also decode anything that conforms to the RawRepresentable type. For example, assume the following enum:

enum Planet: String { case Mercury = "mercury" case Venus = "venus" case Earth = "earth" case Mars = "mars" case Jupiter = "jupiter" case Saturn = "saturn" case Uranus = "uranus" case Neptune = "neptune" // case Pluto = "pluto" =( }

Because Planet is backed by a String raw value type, it is inheriently RawRepresentable. This means you can do let planet = JSON["planet"]?.decode(RawRepresentableDecoder<Planet>) or let planets = JSON["planets"]?.decodeArray(RawRepresentableDecoder<Planet>).