Latest 0.1.2
License MIT
Platforms ios 9.0, requires ARC
Dependencies SwiftyJSON

Carthage compatible
CocoaPods Compatible

SwiftyJSONDecodable is a Swift framework that extends SwiftyJSON to provide simple typesafe decoding of JSON into objects/values via the SwiftyJSONDecodable protocol and helper methods on a JSON extension.


  • iOS 9.0+
  • Xcode 7.2+



Carthage is a decentralized dependency manager that builds your dependencies and provides you with binary frameworks.

To integrate SwiftyJSONDecodable into your Xcode project using Carthage, specify it in your Cartfile:

github "pollarm/SwiftyJSONDecodable"

Run carthage update --platform iOS --no-use-binaries to build the framework and it’s dependencies and drag the built SwiftyJSON.framework and SwiftyJSONDecodable.framework into your Xcode project.


CocoaPods 0.39.0+ is required to build SwiftyJSONDecodable.

To integrate SwiftyJSONDecodable into your Xcode project using CocoaPods, specify it in your Podfile:

platform :ios, '9.0'

pod 'SwiftyJSONDecodable'

Then, run the following command:

$ pod install

Getting started

At the heart of the SwiftyJSONDecodable framework is the SwiftyJSONDecodable protocol:

/// Conform to this if you can be instantiated from a json representation
/// in the form of a SwiftyJSON.JSON
public protocol SwiftyJSONDecodable {

    /// An initialiser that take a JSON and throws
    /// The intention here is that the implementation can `throw` if the json
    /// is malformatted, missing required fields etc.
    init(json: JSON) throws


Extensions on Int, String, Double, Bool are provided in the framework.

An extension on SwiftyJSON provides the following helper methods:

public func decodeArrayForKey<T: SwiftyJSONDecodable>(key: String) throws -> Array<T>?

public func decodeArrayForKey<T: SwiftyJSONDecodable>(key: String) throws -> Array<T>

public func decodeValueForKey<T: SwiftyJSONDecodable>(key: String) throws -> T?

public func decodeValueForKey<T: SwiftyJSONDecodable>(key: String) throws -> T

public func decodeAsValue<T: SwiftyJSONDecodable>() throws -> T?

public func decodeAsValue<T: SwiftyJSONDecodable>() throws -> T

public func decodeAsDictionaryForKey<V: SwiftyJSONDecodable>(key: String) throws -> Dictionary<String, V>


Say you have the following json that you want to decode into values:

    person: {
        firstName: "Tim",
        surname: "Cook",
        address: {
            line1: "1 Infinite Loop"
            line2: "null"
            city: "Cupertino"

And the following types you want to create:

struct Person {
    let firstName : String
    let surname : String
    let address : Address

struct Address {
    let line1 : String
    let line2 : String?
    let city : String

SwiftyJSONDecodable allows you to define the following:

extension Person : SwiftyJSONDecodable {

    init(json: JONS) throws {
        firstName = try json.decodeValueFromKey("firstName")
        surname = try json.decodeValueFromKey("surname")
        address = try json.decodeValueFromKey("address")

extension Address : SwiftyJSONDecodable {

    init(json: JONS) throws {
        line1 = try json.decodeValueFromKey("line1")
        line2 = try json.decodeValueFromKey("line2")
        city = try json.decodeValueFromKey("city")


let person : Person = try json.decodeValueFromKey("person")

As you can see you can nest complex types as long as they conform to SwiftyJSONDecodable.

The reason to use the helper functions on JSON such as decodeValueFromKey rather than use the initializer directly is that the keys can then be built into a keypath as the levels are decoded. This allows detailed error reporting in the ErrorType thrown.

The following ErrorType is used

public indirect enum SwiftyJSONDecodeError : ErrorType {

case NullValue
case WrongType
case InvalidValue(String?)
case ErrorForKey(key: String, error: SwiftyJSONDecodeError)

So for example if line2 in Address was made non-optional, the attempt to decode the above example would result in a SwiftyJSONDecodeError.ErrorForKey being thrown with the following debugDescription: ‘person.address.line2.NullValue’

Latest podspec

    "name": "SwiftyJSONDecodable",
    "version": "0.1.2",
    "summary": "Framework for decoding from SwiftyJSON to well typed objects/values types.",
    "homepage": "",
    "license": {
        "type": "MIT",
        "file": "LICENSE"
    "authors": {
        "Mike Pollard": "[email protected]"
    "social_media_url": "",
    "platforms": {
        "ios": "9.0"
    "requires_arc": true,
    "source": {
        "git": "",
        "tag": "0.1.2"
    "source_files": "SwiftyJSONDecodable/**/*.{h,swift}",
    "dependencies": {
        "SwiftyJSON": [
            "~> 2.3"

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