example of decoding dictionary objects with Argo/FP

decodeDict.swift

import Argo
import Runes

func +<T, V>(lhs: [T: V], rhs: [T: V]) -> [T: V] {
    var dict = lhs
    for (key, val) in rhs {
        dict[key] = val
    }

    return dict
}

func decodeDict<T>(j: JSONValue) -> [String: T]? {
    switch j {
    case let .JSONObject(xs):
        return reduce(xs, [:]) { (accum, pair) in
            if let x: T = pair.1.value(), xs = accum {
                return xs + [pair.0: x]
            }

            return accum
        }
    default: return .None
    }
}

struct Notifications: JSONDecodable {
    let email: [String: Bool]
    let push: [String: Bool]

    static func create(email: [String: Bool])(push: [String: Bool]) -> Notifications {
        return Notifications(email: email, push: push)
    }

    static func decode(j: JSONValue) -> Notifications? {
        let email: [String: Bool]? = j["email"] >>- decodeDict
        let push: [String: Bool]? = j["push"] >>- decodeDict
        return Notifications.create
            <^> email
            <*> push
    }
}

let json: AnyObject = [ "notifications" : [[
    "email": [
        "balance": true,
        "guest_joins": true,
        "low_battery": false
    ],
    "push": [
        "balance": true,
        "guest_joins": true,
        "low_battery": true
    ]
]]]

let val = JSONValue.parse(json)["notifications"]

let notifications: [Notifications]? = val >>- JSONValue.mapDecode