Better way to use SwiftyJSON with custom models

json, json-model-mapping, protocol-oriented, swiftyjson, type-safe



A microframework that helps to use Swifty JSON with your custom models in a easy and type-safe way

Carthage compatible Build Status codecov


The full motivation and description is here

For the following JSON:

  "name": "John",
  "age": 25,
  "isMarried": false,
  "height": 170.0,
  "address": {
  	"city": "San-Fransisco",
  	"country": "USA"
  "hobbies": ["bouldering", "guitar", "swift:)"]

to map to the following model:

struct Person {
    let name: String
    let age: Int
    let isMarried: Bool
    let height: Double
    let city: String
    let country: String
    let hobbies: [String]?

Instead of the following:

extension Person {
    init?(jsonDict: [String: Any]) {
        guard let name = jsonDict["name"] as? String,
            let age = jsonDict["age"] as? Int,
            let isMarried = jsonDict["isMarried"] as? Bool,
            let height = jsonDict["height"] as? Double,
            let address = jsonDict["address"] as? [String: Any],
            let city = address["city"] as? String,
            let country = address["country"] as? String
            else {
            return nil
        = name
        self.age = age
        self.isMarried = isMarried
        self.height = height = city = country
        hobbies = jsonDict["hobbies"] as? [String]

We get the following:

import SwiftyJSONModel

extension Person: JSONModelType {
    enum PropertyKey: String {
        case name, age, isMarried, height, hobbies
        case address, country, city
    init(object: JSONObject<PropertyKey>) throws {
        name = try object.value(for: .name)
        age = try object.value(for: .age)
        isMarried = try object.value(for: .isMarried)
        height = try object.value(for: .height)
        city = try object.value(for: .address, .city) // Accessing nested json
        country = try object.value(for: .address, .country) // Accessing nested json
        hobbies = try object.value(for: .hobbies)
    var dictValue: [PropertyKey : JSONRepresentable?] {
        return [
            .name: name,
            .age: age,
            .isMarried: isMarried,
            .height: height,
            .city: city,
            .country: country,
            .hobbies: hobbies?.jsonRepresantable,

What we improved:

  • Keys are now restricted to the PropertyKey enum and we will have a compile error if we try to use something different.
  • Autocomplition will help us navigate through available keys
  • The constructor now throws which means that the init will fail if some value or it's type was different from what we expected and the Error will tell us exactly which property in JSON was wrong
  • The type of the value for key is now inferred from the property we specify. That means we do not need to have all this boilerplate code with casting to String or Int. It will be done for us.


CocoaPods (iOS 8+)

You can use CocoaPods to install SwiftyJSONModel by adding it to your Podfile:

platform :ios, '8.0'

target 'MyApp' do
pod 'SwiftyJSONModel'

Note that this requires CocoaPods version 36, and your iOS deployment target to be at least 8.0:

Carthage (iOS 8+)

You can use Carthage to install SwiftyJSONModel by adding it to your Cartfile:

github "alickbass/SwiftyJSONModel"