SwiftyJSON makes it easy to deal with JSON data in Swift.
- Why is the typical JSON handling in Swift NOT good
- Requirements
- Integration
- Usage
- Work with Alamofire
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://dev.twitter.com/docs/api/1.1/get/statuses/home_timeline).
The code would look like this:
let JSONObject: AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) if let statusesArray = JSONObject as? [AnyObject], let status = statusesArray[0] as? [String: AnyObject], let user = status["user"] as? [String: AnyObject], 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:
let JSONObject: AnyObject? = NSJSONSerialization.JSONObjectWithData(data, options: nil, error: nil) if let username = (((JSONObject as? [AnyObject])?[0] as? [String: AnyObject])?["user"] as? [String: AnyObject])?["name"] as? String { // What a disaster }
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 println(json[999999]["wrong_key"]["wrong_name"]) }
Requirements
- iOS 7.0+ / Mac OS X 10.9+
- Xcode 6.1
Integration
CocoaPods (iOS 8+, OS X 10.9+)
You can use Cocoapods to install SwiftyJSON
by adding it to your Podfile
:
platform :ios, ‘8.0‘ use_frameworks! target ‘MyApp‘ do pod ‘SwiftyJSON‘, ‘~> 2.2.0‘ end
Note that it needs you to install CocoaPods 36 version, and requires your iOS deploy target >= 8.0:
Carthage (iOS 8+, OS X 10.9+)
You can use Carthage to install SwiftyJSON
by adding it to your Cartfile
:
github "SwiftyJSON/SwiftyJSON" >= 2.2.0
Manually (iOS 7+, OS X 10.9+)
To use this library in your project manually you may:
- for Projects, just drag SwiftyJSON.swift to the project tree
- for Workspaces, include the whole SwiftyJSON.xcodeproj
Usage
Initialization
import SwiftyJSON
let json = JSON(data: dataFromNetworking)
let json = JSON(jsonObject)
if let dataFromString = jsonString.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false) { let json = JSON(data: dataFromString) }
Subscript
//Getting a double from a JSON Array let name = json[0].double
//Getting a string from a JSON Dictionary let name = json["name"].stringValue
//Getting a string using a path to the element let path = [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
Loop
//If json is .Dictionary for (key: String, subJson: 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: String, subJson: JSON) in json { //Do something you want }
Error
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 get
nil
without a reason. - not an array or a dictionary, the app may crash with an "unrecognised selector" exception.
It will never happen in SwiftyJSON.
let json = JSON(["name", "age"]) if let name = json[999].string { //Do something you want } else { println(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 { println(json["address"].error) // "Dictionary["address"] does not exist" }
let json = JSON(12345) if let age = json[0].string { //Do something you want } else { println(json[0]) // "Array[0] failure, It is not an array" println(json[0].error) // "Array[0] failure, It is not an array" } if let name = json["name"].string { //Do something you want } else { println(json["name"]) // "Dictionary[\"name"] failure, It is not an dictionary" println(json["name"].error) // "Dictionary[\"name"] failure, It is not an dictionary" }
Optional getter
//NSNumber if let id = json["user"]["favourites_count"].number { //Do something you want } else { //Print the error println(json["user"]["favourites_count"].error) }
//String if let id = json["user"]["name"].string { //Do something you want } else { //Print the error println(json["user"]["name"]) }
//Bool if let id = json["user"]["is_translator"].bool { //Do something you want } else { //Print the error println(json["user"]["is_translator"]) }
//Int if let id = json["user"]["id"].int { //Do something you want } else { //Print the error println(json["user"]["id"]) } ...
Non-optional getter
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 a 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
Setter
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.dictionary = ["name":"Jack", "age":25]
Raw object
let jsonObject: AnyObject = json.object
if let jsonObject: AnyObject = 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 }
Literal convertibles
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 = ["list",3,"what"] json[path] = "that"
Work with Alamofire
SwiftyJSON nicely wraps the result of the Alamofire JSON response handler:
Alamofire.request(.GET, url, parameters: parameters) .responseJSON { (req, res, json, error) in if(error != nil) { NSLog("Error: \(error)") println(req) println(res) } else { NSLog("Success: \(url)") var json = JSON(json!) } } https://github.com/SwiftyJSON/SwiftyJSON