SwiftyJSON

SwiftyJSON makes it easy to deal with JSON data in Swift.

1. Why is the typical JSON handling in Swift NOT good
2. Requirements
3. Integration
4. Usage
   • Initialization
   • Subscript
   • Loop
   • Error
   • Optional getter
   • Non-optional getter
   • Setter
   • Raw object
   • Literal convertibles
   • Merging
5. Work with Alamofire

For Legacy Swift support, take a look at the swift2 branch

中文介绍

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:

iflet 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:

iflet JSONObject =tryJSONSerialization.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:

letjson=JSON(data: dataFromNetworking)iflet 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.

letjson=JSON(data: dataFromNetworking)iflet 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"])}

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 to install SwiftyJSONby adding it to your Podfile:

platform:ios,'8.0'use_frameworks!target'MyApp'dopod'SwiftyJSON'end

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

Swift Package Manager

You can use The Swift Package Manager to install SwiftyJSON by adding the proper description to your Package.swift file:

import PackageDescription
letpackage=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

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

import SwiftyJSON

letjson=JSON(data: dataFromNetworking)

letjson=JSON(jsonObject)

iflet dataFromString = jsonString.data(using:.utf8, allowLossyConversion:false){letjson=JSON(data: dataFromString)}

Subscript

//Getting a double from a JSON Array
letname=json[0].double

//Getting an array of string from a JSON Array
letarrayNames=json["users"].arrayValue.map({$0["name"].stringValue})

//Getting a string from a JSON Dictionary
letname=json["name"].stringValue

//Getting a string using a path to the element
letpath:[JSONSubscriptType]=[1,"list",2,"name"]letname=json[path].string
//Just the same
letname=json[1]["list"][2]["name"].string
//Alternatively
letname=json[1,"list",2,"name"].string

//With a hard way
letname=json[].string

//With a custom way
letkeys:[SubscriptType]=[1,"list",2,"name"]letname=json[keys].string

Loop

//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
}

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 be assigned 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.

letjson=JSON(["name","age"])iflet name =json[999].string {
//Do something you want
}else{print(json[999].error) // "Array[999] is out of bounds"
}

letjson=JSON(["name":"Jack","age":25])iflet name =json["address"].string {
//Do something you want
}else{print(json["address"].error) // "Dictionary["address"] does not exist"
}

letjson=JSON(12345)iflet 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"
}iflet 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

//NSNumber
iflet id =json["user"]["favourites_count"].number {
//Do something you want
}else{
//Print the error
print(json["user"]["favourites_count"].error)}

//String
iflet id =json["user"]["name"].string {
//Do something you want
}else{
//Print the error
print(json["user"]["name"])}

//Bool
iflet id =json["user"]["is_translator"].bool {
//Do something you want
}else{
//Print the error
print(json["user"]["is_translator"])}

//Int
iflet id =json["user"]["id"].int {
//Do something you want
}else{
//Print the error
print(json["user"]["id"])}...

Non-optional getter

Non-optional getter is named xxxValue

//If not a Number or nil, return 0
letid:Int=json["id"].intValue

//If not a String or nil, return ""
letname:String=json["name"].stringValue

//If not an Array or nil, return []
letlist:Array<JSON>=json["list"].arrayValue

//If not a Dictionary or nil, return [:]
letuser:Dictionary<String,JSON>=json["user"].dictionaryValue

Setter

json["name"]=JSON("new-name")json[0]=JSON(1)

json["id"].int =1234567890json["coordinate"].double =8766.766json["name"].string ="Jack"
json.arrayObject =[1,2,3,4]
json.dictionaryObject =["name":"Jack","age":25]

Raw object

letjsonObject:Any= json.object

if let jsonObject:Any= json.rawValue

//convert the JSON to raw NSData
iflet data = json.rawData(){
//Do something you want
}

//convert the JSON to a raw String
iflet string = json.rawString(){
//Do something you want
}

Existence

//shows you whether value specified in JSON or not
if json["name"].exists()

Literal convertibles

For more info about literal convertibles: Swift Literal Convertibles

//StringLiteralConvertible
letjson:JSON="I'm a json"

//IntegerLiteralConvertible
letjson:JSON=12345

//BooleanLiteralConvertible
letjson:JSON=true

//FloatLiteralConvertible
letjson:JSON=2.8765

//DictionaryLiteralConvertible
letjson:JSON=["I":"am","a":"json"]

//ArrayLiteralConvertible
letjson:JSON=["I","am","a","json"]

//NilLiteralConvertible
letjson:JSON=nil

//With subscript in array
varjson:JSON=[1,2,3]json[0]=100json[1]=200json[2]=300json[999]=300 //Don't worry, nothing will happen

//With subscript in dictionary
varjson: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
varjson:JSON=["name":"Jack","age":25,"list":["a","b","c",["what":"this"]]]json["list"][3]["what"]="that"json["list",3,"what"]="that"letpath:[JSONSubscriptType]=["list",3,"what"]json[path]="that"

//With other JSON objects
letuser:JSON=["username":"Steve","password":"supersecurepassword"]letauth: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 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.

letoriginal:JSON=["first_name":"John","age":20,"skills":["Coding","Reading"],"address":["street":"Front St","zip":"12345",]]letupdate:JSON=["last_name":"Doe","age":21,"skills":["Writing"],"address":["zip":"12342","city":"New York City"]]letupdated= 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"
// ]
// ]

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":

letdict=["1":2,"2":"two","3":nil]as[String:Any?]letjson=JSON(dict)letrepresentation= json.rawString(options:[.castNilToNSNull:true])
// representation is "{\"1\":2,\"2\":\"two\",\"3\":null}", which represents {"1":2,"2":"two","3":null}

Work with Alamofire

SwiftyJSON nicely wraps the result of the Alamofire JSON response handler:

Alamofire.request(url, method:.get).validate().responseJSON{ response inswitch response.result {case.success(let value):letjson=JSON(value)print("JSON: \(json)")case.failure(let error):print(error)}}