SwiftyJSON 中文介绍

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
5. 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:

iflet statusesArray =try?NSJSONSerialization.JSONObjectWithData(data, options:.AllowFragments)as?[[String:AnyObject]],let user =statusesArray[0]["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:

iflet JSONObject =tryNSJSONSerialization.JSONObjectWithData(data, options:.AllowFragments)as?[[String:AnyObject]],let username =(JSONObject[0]["user"]as?[String:AnyObject])?["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

Swift 3

Integration

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:"2.3.3"..<Version.max)])

Usage

Initialization

import SwiftyJSON

letjson=JSON(data: dataFromNetworking)

letjson=JSON(jsonObject)

iflet dataFromString = jsonString.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion:false){letjson=JSON(data: dataFromString)}

Subscript

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

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

//Getting a string using a path to the element
letpath=[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 a 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.dictionary =["name":"Jack","age":25]

Raw object

letjsonObject:AnyObject= json.object

if let jsonObject:AnyObject= 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
}

Existance

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

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=["list",3,"what"]json[path]="that"

Work with Alamofire

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

Alamofire.request(.GET, url).validate().responseJSON{ response inswitch response.result {case.Success:iflet value = response.result.value {letjson=JSON(value)print("JSON: \(json)")}case.Failure(let error):print(error)}}