SwiftyJSON makes it easy to deal with JSON data in Swift.
For Legacy Swift support, take a look at the swift2 branch
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://dev.twitter.com/docs/api/1.1/get/statuses/home_timeline).
The code would look like this:
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:
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:
let json = 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.
let json = JSON(data: dataFromNetworking) if let userName = json[999999]["wrong_key"]["wrong_name"].string { //Calm down, take it easy, the ".string" property still produces the correct Optional String type with safety } else { //Print the error print(json[999999]["wrong_key"]["wrong_name"]) }
You can use CocoaPods to install SwiftyJSON
by adding it to your Podfile
:
platform :ios, '8.0' use_frameworks! target 'MyApp' do pod 'SwiftyJSON' end
Note that this requires CocoaPods version 36, and your iOS deployment target to be at least 8.0:
You can use Carthage to install SwiftyJSON
by adding it to your Cartfile
:
github "SwiftyJSON/SwiftyJSON"
You can use The Swift Package Manager to install SwiftyJSON
by adding the proper description to your Package.swift
file:
import PackageDescription let package = Package( name: "YOUR_PROJECT_NAME", targets: [], dependencies: [ .Package(url: "https://github.com/SwiftyJSON/SwiftyJSON.git", versions: Version(1,0,0)..<Version(3, .max, .max)), ] )
Note that the Swift Package Manager is still in early design and development, for more information checkout its GitHub Page
To use this library in your project manually you may:
import SwiftyJSON
let json = JSON(data: dataFromNetworking)
let json = JSON(jsonObject)
if let dataFromString = jsonString.data(using: .utf8, allowLossyConversion: false) { let json = JSON(data: dataFromString) }
//Getting a double from a JSON Array let name = json[0].double
//Getting an array of string from a JSON Array let arrayNames = json["users"].arrayValue.map({$0["name"].stringValue})
//Getting a string from a JSON Dictionary let name = json["name"].stringValue
//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
//With a hard way let name = json[].string
//With a custom way let keys:[SubscriptType] = [1,"list",2,"name"] let name = json[keys].string
//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
//If json is .Array //The `index` is 0..<json.count's string value for (index,subJson):(String, JSON) in json { //Do something you want }
Use a subscript to get/set a value in an Array or Dictionary
If the JSON is:
nil
without a reason.This will never happen in SwiftyJSON.
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" }
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" }
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" }
//NSNumber if let id = json["user"]["favourites_count"].number { //Do something you want } else { //Print the error print(json["user"]["favourites_count"].error) }
//String if let id = json["user"]["name"].string { //Do something you want } else { //Print the error print(json["user"]["name"]) }
//Bool if let id = json["user"]["is_translator"].bool { //Do something you want } else { //Print the error print(json["user"]["is_translator"]) }
//Int if let id = json["user"]["id"].int { //Do something you want } else { //Print the error print(json["user"]["id"]) } ...
Non-optional getter is named xxxValue
//If not a Number or nil, return 0 let id: Int = json["id"].intValue
//If not a String or nil, return "" let name: String = json["name"].stringValue
//If not an Array or nil, return [] let list: Array<JSON> = json["list"].arrayValue
//If not a Dictionary or nil, return [:] let user: Dictionary<String, JSON> = json["user"].dictionaryValue
json["name"] = JSON("new-name") json[0] = JSON(1)
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]
let jsonObject: Any = json.object
if let jsonObject: Any = json.rawValue
//convert the JSON to raw NSData if let data = json.rawData() { //Do something you want }
//convert the JSON to a raw String if let string = json.rawString() { //Do something you want }
//shows you whether value specified in JSON or not if json["name"].exists()
For more info about literal convertibles: Swift Literal Convertibles
//StringLiteralConvertible let json: JSON = "I'm a json"
//IntegerLiteralConvertible let json: JSON = 12345
//BooleanLiteralConvertible let json: JSON = true
//FloatLiteralConvertible let json: JSON = 2.8765
//DictionaryLiteralConvertible let json: JSON = ["I":"am", "a":"json"]
//ArrayLiteralConvertible let json: JSON = ["I", "am", "a", "json"]
//NilLiteralConvertible let json: JSON = nil
//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
//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
//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"
//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" ]
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:
JSON.Type.array
the values form the array found in the other
JSON getting appended to the original JSON's array value.JSON.Type.dictionary
both JSON-values are getting merged the same way the encapsulating JSON is merged.In case, where two fields in a JSON have a 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.
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" // ] // ]
There are two options available:
nil
as "null"
: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}
SwiftyJSON nicely wraps the result of the Alamofire JSON response handler:
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) } }