base on The better way to deal with JSON data in Swift. # SwiftyJSON [](https://github.com/Carthage/Carthage)   [](https://houndci.com) SwiftyJSON makes it easy to deal with JSON data in Swift. Platform | Build Status ---------| --------------| *OS | [](https://travis-ci.org/SwiftyJSON/SwiftyJSON) | [Linux](https://github.com/IBM-Swift/SwiftyJSON) | [](https://travis-ci.org/IBM-Swift/SwiftyJSON) | 1. [Why is the typical JSON handling in Swift NOT good](#why-is-the-typical-json-handling-in-swift-not-good) 2. [Requirements](#requirements) 3. [Integration](#integration) 4. [Usage](#usage) - [Initialization](#initialization) - [Subscript](#subscript) - [Loop](#loop) - [Error](#error) - [Optional getter](#optional-getter) - [Non-optional getter](#non-optional-getter) - [Setter](#setter) - [Raw object](#raw-object) - [Literal convertibles](#literal-convertibles) - [Merging](#merging) - [Removing elements](#removing-elements) 5. [Work with Alamofire](#work-with-alamofire) 6. [Work with Moya](#work-with-moya) 7. [SwiftyJSON Model Generator](#swiftyjson-model-generator) ## Why is the typical JSON handling in Swift NOT good? Swift is very strict about types. But although explicit typing is good for saving us from mistakes, it becomes painful when dealing with JSON and other areas that are, by nature, implicit about types. Take the Twitter API for example. Say we want to retrieve a user's "name" value of some tweet in Swift (according to [Twitter's API](https://developer.twitter.com/en/docs/tweets/timelines/api-reference/get-statuses-home_timeline)). The code would look like this: ```swift if let statusesArray = try? JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [[String: Any]], let user = statusesArray[0]["user"] as? [String: Any], let username = user["name"] as? String { // Finally we got the username } ``` It's not good. Even if we use optional chaining, it would be messy: ```swift if let JSONObject = try JSONSerialization.jsonObject(with: data, options: .allowFragments) as? [[String: Any]], let username = (JSONObject[0]["user"] as? [String: Any])?["name"] as? String { // There's our username } ``` An unreadable mess--for something that should really be simple! With SwiftyJSON all you have to do is: ```swift let json = try? JSON(data: dataFromNetworking) if let userName = json[0]["user"]["name"].string { //Now you got your value } ``` And don't worry about the Optional Wrapping thing. It's done for you automatically. ```swift let json = try? JSON(data: dataFromNetworking) let result = json[999999]["wrong_key"]["wrong_name"] if let userName = result.string { //Calm down, take it easy, the ".string" property still produces the correct Optional String type with safety } else { //Print the error print(result.error) } ``` ## Requirements - iOS 8.0+ | macOS 10.10+ | tvOS 9.0+ | watchOS 2.0+ - Xcode 8 ## Integration #### CocoaPods (iOS 8+, OS X 10.9+) You can use [CocoaPods](http://cocoapods.org/) to install `SwiftyJSON` by adding it to your `Podfile`: ```ruby platform :ios, '8.0' use_frameworks! target 'MyApp' do pod 'SwiftyJSON', '~> 4.0' end ``` #### Carthage (iOS 8+, OS X 10.9+) You can use [Carthage](https://github.com/Carthage/Carthage) to install `SwiftyJSON` by adding it to your `Cartfile`: ``` github "SwiftyJSON/SwiftyJSON" ~> 4.0 ``` If you use Carthage to build your dependencies, make sure you have added `SwiftyJSON.framework` to the "Linked Frameworks and Libraries" section of your target, and have included them in your Carthage framework copying build phase. #### Swift Package Manager You can use [The Swift Package Manager](https://swift.org/package-manager) to install `SwiftyJSON` by adding the proper description to your `Package.swift` file: ```swift // swift-tools-version:4.0 import PackageDescription let package = Package( name: "YOUR_PROJECT_NAME", dependencies: [ .package(url: "https://github.com/SwiftyJSON/SwiftyJSON.git", from: "4.0.0"), ] ) ``` Then run `swift build` whenever you get prepared. #### Manually (iOS 7+, OS X 10.9+) To use this library in your project manually you may: 1. for Projects, just drag SwiftyJSON.swift to the project tree 2. for Workspaces, include the whole SwiftyJSON.xcodeproj ## Usage #### Initialization ```swift import SwiftyJSON ``` ```swift let json = try? JSON(data: dataFromNetworking) ``` Or ```swift let json = JSON(jsonObject) ``` Or ```swift if let dataFromString = jsonString.data(using: .utf8, allowLossyConversion: false) { let json = JSON(data: dataFromString) } ``` #### Subscript ```swift // Getting a double from a JSON Array let name = json[0].double ``` ```swift // Getting an array of string from a JSON Array let arrayNames = json["users"].arrayValue.map {$0["name"].stringValue} ``` ```swift // Getting a string from a JSON Dictionary let name = json["name"].stringValue ``` ```swift // Getting a string using a path to the element let path: [JSONSubscriptType] = [1,"list",2,"name"] let name = json[path].string // Just the same let name = json[1]["list"][2]["name"].string // Alternatively let name = json[1,"list",2,"name"].string ``` ```swift // With a hard way let name = json[].string ``` ```swift // With a custom way let keys:[JSONSubscriptType] = [1,"list",2,"name"] let name = json[keys].string ``` #### Loop ```swift // If json is .Dictionary for (key,subJson):(String, JSON) in json { // Do something you want } ``` *The first element is always a String, even if the JSON is an Array* ```swift // If json is .Array // The `index` is 0..<json.count's string value for (index,subJson):(String, JSON) in json { // Do something you want } ``` #### Error ##### SwiftyJSON 4.x SwiftyJSON 4.x introduces an enum type called `SwiftyJSONError`, which includes `unsupportedType`, `indexOutOfBounds`, `elementTooDeep`, `wrongType`, `notExist` and `invalidJSON`, at the same time, `ErrorDomain` are being replaced by `SwiftyJSONError.errorDomain`. Note: Those old error types are deprecated in SwiftyJSON 4.x and will be removed in the future release. ##### SwiftyJSON 3.x Use a subscript to get/set a value in an Array or Dictionary If the JSON is: * an array, the app may crash with "index out-of-bounds." * a dictionary, it will be assigned to `nil` without a reason. * not an array or a dictionary, the app may crash with an "unrecognised selector" exception. This will never happen in SwiftyJSON. ```swift let json = JSON(["name", "age"]) if let name = json[999].string { // Do something you want } else { print(json[999].error!) // "Array[999] is out of bounds" } ``` ```swift let json = JSON(["name":"Jack", "age": 25]) if let name = json["address"].string { // Do something you want } else { print(json["address"].error!) // "Dictionary["address"] does not exist" } ``` ```swift let json = JSON(12345) if let age = json[0].string { // Do something you want } else { print(json[0]) // "Array[0] failure, It is not an array" print(json[0].error!) // "Array[0] failure, It is not an array" } if let name = json["name"].string { // Do something you want } else { print(json["name"]) // "Dictionary[\"name"] failure, It is not an dictionary" print(json["name"].error!) // "Dictionary[\"name"] failure, It is not an dictionary" } ``` #### Optional getter ```swift // NSNumber if let id = json["user"]["favourites_count"].number { // Do something you want } else { // Print the error print(json["user"]["favourites_count"].error!) } ``` ```swift // String if let id = json["user"]["name"].string { // Do something you want } else { // Print the error print(json["user"]["name"].error!) } ``` ```swift // Bool if let id = json["user"]["is_translator"].bool { // Do something you want } else { // Print the error print(json["user"]["is_translator"].error!) } ``` ```swift // Int if let id = json["user"]["id"].int { // Do something you want } else { // Print the error print(json["user"]["id"].error!) } ... ``` #### Non-optional getter Non-optional getter is named `xxxValue` ```swift // If not a Number or nil, return 0 let id: Int = json["id"].intValue ``` ```swift // If not a String or nil, return "" let name: String = json["name"].stringValue ``` ```swift // If not an Array or nil, return [] let list: Array<JSON> = json["list"].arrayValue ``` ```swift // If not a Dictionary or nil, return [:] let user: Dictionary<String, JSON> = json["user"].dictionaryValue ``` #### Setter ```swift json["name"] = JSON("new-name") json[0] = JSON(1) ``` ```swift json["id"].int = 1234567890 json["coordinate"].double = 8766.766 json["name"].string = "Jack" json.arrayObject = [1,2,3,4] json.dictionaryObject = ["name":"Jack", "age":25] ``` #### Raw object ```swift let rawObject: Any = json.object ``` ```swift let rawValue: Any = json.rawValue ``` ```swift //convert the JSON to raw NSData do { let rawData = try json.rawData() //Do something you want } catch { print("Error \(error)") } ``` ```swift //convert the JSON to a raw String if let rawString = json.rawString() { //Do something you want } else { print("json.rawString is nil") } ``` #### Existence ```swift // shows you whether value specified in JSON or not if json["name"].exists() ``` #### Literal convertibles For more info about literal convertibles: [Swift Literal Convertibles](http://nshipster.com/swift-literal-convertible/) ```swift // StringLiteralConvertible let json: JSON = "I'm a json" ``` ```swift // IntegerLiteralConvertible let json: JSON = 12345 ``` ```swift // BooleanLiteralConvertible let json: JSON = true ``` ```swift // FloatLiteralConvertible let json: JSON = 2.8765 ``` ```swift // DictionaryLiteralConvertible let json: JSON = ["I":"am", "a":"json"] ``` ```swift // ArrayLiteralConvertible let json: JSON = ["I", "am", "a", "json"] ``` ```swift // With subscript in array var json: JSON = [1,2,3] json[0] = 100 json[1] = 200 json[2] = 300 json[999] = 300 // Don't worry, nothing will happen ``` ```swift // With subscript in dictionary var json: JSON = ["name": "Jack", "age": 25] json["name"] = "Mike" json["age"] = "25" // It's OK to set String json["address"] = "L.A." // Add the "address": "L.A." in json ``` ```swift // Array & Dictionary var json: JSON = ["name": "Jack", "age": 25, "list": ["a", "b", "c", ["what": "this"]]] json["list"][3]["what"] = "that" json["list",3,"what"] = "that" let path: [JSONSubscriptType] = ["list",3,"what"] json[path] = "that" ``` ```swift // With other JSON objects let user: JSON = ["username" : "Steve", "password": "supersecurepassword"] let auth: JSON = [ "user": user.object, // use user.object instead of just user "apikey": "supersecretapitoken" ] ``` #### Merging It is possible to merge one JSON into another JSON. Merging a JSON into another JSON adds all non existing values to the original JSON which are only present in the `other` JSON. If both JSONs contain a value for the same key, _mostly_ this value gets overwritten in the original JSON, but there are two cases where it provides some special treatment: - In case of both values being a `JSON.Type.array` the values form the array found in the `other` JSON getting appended to the original JSON's array value. - In case of both values being a `JSON.Type.dictionary` both JSON-values are getting merged the same way the encapsulating JSON is merged. In a case where two fields in a JSON have different types, the value will get always overwritten. There are two different fashions for merging: `merge` modifies the original JSON, whereas `merged` works non-destructively on a copy. ```swift let original: JSON = [ "first_name": "John", "age": 20, "skills": ["Coding", "Reading"], "address": [ "street": "Front St", "zip": "12345", ] ] let update: JSON = [ "last_name": "Doe", "age": 21, "skills": ["Writing"], "address": [ "zip": "12342", "city": "New York City" ] ] let updated = original.merge(with: update) // [ // "first_name": "John", // "last_name": "Doe", // "age": 21, // "skills": ["Coding", "Reading", "Writing"], // "address": [ // "street": "Front St", // "zip": "12342", // "city": "New York City" // ] // ] ``` #### Removing elements If you are storing dictionaries, you can remove elements using `dictionaryObject.removeValue(forKey:)`. This mutates the JSON object in place. For example: ```swift var object = JSON([ "one": ["color": "blue"], "two": ["city": "tokyo", "country": "japan", "foods": [ "breakfast": "tea", "lunch": "sushi" ] ] ]) ``` Lets remove the `country` key: ```swift object["two"].dictionaryObject?.removeValue(forKey: "country") ``` If you `print(object)`, you'll see that the `country` key no longer exists. ```json { "one" : { "color" : "blue" }, "two" : { "city" : "tokyo", "foods" : { "breakfast" : "tea", "lunch" : "sushi" } } } ``` This also works for nested dictionaries: ```swift object["two"]["foods"].dictionaryObject?.removeValue(forKey: "breakfast") ``` ```json { "one" : { "color" : "blue" }, "two" : { "city" : "tokyo", "foods" : { "lunch" : "sushi" } } } ``` ## String representation There are two options available: - use the default Swift one - use a custom one that will handle optionals well and represent `nil` as `"null"`: ```swift let dict = ["1":2, "2":"two", "3": nil] as [String: Any?] let json = JSON(dict) let representation = json.rawString(options: [.castNilToNSNull: true]) // representation is "{\"1\":2,\"2\":\"two\",\"3\":null}", which represents {"1":2,"2":"two","3":null} ``` ## Work with [Alamofire](https://github.com/Alamofire/Alamofire) SwiftyJSON nicely wraps the result of the Alamofire JSON response handler: ```swift Alamofire.request(url, method: .get).validate().responseJSON { response in switch response.result { case .success(let value): let json = JSON(value) print("JSON: \(json)") case .failure(let error): print(error) } } ``` We also provide an extension of Alamofire for serializing NSData to SwiftyJSON's JSON. See: [Alamofire-SwiftyJSON](https://github.com/SwiftyJSON/Alamofire-SwiftyJSON) ## Work with [Moya](https://github.com/Moya/Moya) SwiftyJSON parse data to JSON: ```swift let provider = MoyaProvider<Backend>() provider.request(.showProducts) { result in switch result { case let .success(moyaResponse): let data = moyaResponse.data let json = JSON(data: data) // convert network data to json print(json) case let .failure(error): print("error: \(error)") } } ``` ## SwiftyJSON Model Generator Tools to generate SwiftyJSON Models * [JSON Export](https://github.com/Ahmed-Ali/JSONExport) ", Assign "at most 3 tags" to the expected json: {"id":"10856","tags":[]} "only from the tags list I provide: [{"id":77,"name":"3d"},{"id":89,"name":"agent"},{"id":17,"name":"ai"},{"id":54,"name":"algorithm"},{"id":24,"name":"api"},{"id":44,"name":"authentication"},{"id":3,"name":"aws"},{"id":27,"name":"backend"},{"id":60,"name":"benchmark"},{"id":72,"name":"best-practices"},{"id":39,"name":"bitcoin"},{"id":37,"name":"blockchain"},{"id":1,"name":"blog"},{"id":45,"name":"bundler"},{"id":58,"name":"cache"},{"id":21,"name":"chat"},{"id":49,"name":"cicd"},{"id":4,"name":"cli"},{"id":64,"name":"cloud-native"},{"id":48,"name":"cms"},{"id":61,"name":"compiler"},{"id":68,"name":"containerization"},{"id":92,"name":"crm"},{"id":34,"name":"data"},{"id":47,"name":"database"},{"id":8,"name":"declarative-gui "},{"id":9,"name":"deploy-tool"},{"id":53,"name":"desktop-app"},{"id":6,"name":"dev-exp-lib"},{"id":59,"name":"dev-tool"},{"id":13,"name":"ecommerce"},{"id":26,"name":"editor"},{"id":66,"name":"emulator"},{"id":62,"name":"filesystem"},{"id":80,"name":"finance"},{"id":15,"name":"firmware"},{"id":73,"name":"for-fun"},{"id":2,"name":"framework"},{"id":11,"name":"frontend"},{"id":22,"name":"game"},{"id":81,"name":"game-engine "},{"id":23,"name":"graphql"},{"id":84,"name":"gui"},{"id":91,"name":"http"},{"id":5,"name":"http-client"},{"id":51,"name":"iac"},{"id":30,"name":"ide"},{"id":78,"name":"iot"},{"id":40,"name":"json"},{"id":83,"name":"julian"},{"id":38,"name":"k8s"},{"id":31,"name":"language"},{"id":10,"name":"learning-resource"},{"id":33,"name":"lib"},{"id":41,"name":"linter"},{"id":28,"name":"lms"},{"id":16,"name":"logging"},{"id":76,"name":"low-code"},{"id":90,"name":"message-queue"},{"id":42,"name":"mobile-app"},{"id":18,"name":"monitoring"},{"id":36,"name":"networking"},{"id":7,"name":"node-version"},{"id":55,"name":"nosql"},{"id":57,"name":"observability"},{"id":46,"name":"orm"},{"id":52,"name":"os"},{"id":14,"name":"parser"},{"id":74,"name":"react"},{"id":82,"name":"real-time"},{"id":56,"name":"robot"},{"id":65,"name":"runtime"},{"id":32,"name":"sdk"},{"id":71,"name":"search"},{"id":63,"name":"secrets"},{"id":25,"name":"security"},{"id":85,"name":"server"},{"id":86,"name":"serverless"},{"id":70,"name":"storage"},{"id":75,"name":"system-design"},{"id":79,"name":"terminal"},{"id":29,"name":"testing"},{"id":12,"name":"ui"},{"id":50,"name":"ux"},{"id":88,"name":"video"},{"id":20,"name":"web-app"},{"id":35,"name":"web-server"},{"id":43,"name":"webassembly"},{"id":69,"name":"workflow"},{"id":87,"name":"yaml"}]" returns me the "expected json"