SwiftyJSON 让在 Swift 中处理 JSON 数据变得容易。
Swift 对类型要求非常严格。虽然显式类型检查能帮助我们避免错误,但在处理 JSON 和其他本质上对类型隐式化的领域时,它会变得非常痛苦。
以 Twitter API 为例。假设我们想在 Swift 中检索一条推文中用户的“name”值 (根据 Twitter 的 API https://dev.twitter.com/docs/api/1.1/get/statuses/home_timeline)。
代码看起来会像这样
if let 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
}
这不好。
即使我们使用可选链,也会很混乱
if let JSONObject = try NSJSONSerialization.JSONObjectWithData(data, options: .AllowFragments) as? [[String: AnyObject]],
let username = (JSONObject[0]["user"] as? [String: AnyObject])?["name"] as? String {
// There's our username
}
一段难以阅读的代码--对于一个原本应该很简单的事情!
使用 SwiftyJSON,你只需要这样做
let json = JSON(data: dataFromNetworking)
if let userName = json[0]["user"]["name"].string {
//Now you got your value
}
不用担心 Optional Wrapping 的问题。它会自动为你完成。
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"])
}
Swift 3
您可以使用 The Swift Package Manager 安装 SwiftyJSON
,方法是在您的 Package.swift
文件中添加正确的描述
import PackageDescription
let package = Package(
name: "YOUR_PROJECT_NAME",
targets: [],
dependencies: [
.Package(url: "https://github.com/SwiftyJSON/SwiftyJSON.git", versions: "2.3.3" ..< Version.max)
]
)
import SwiftyJSON
let json = JSON(data: dataFromNetworking)
let json = JSON(jsonObject)
if let dataFromString = jsonString.dataUsingEncoding(NSUTF8StringEncoding, allowLossyConversion: false) {
let json = JSON(data: dataFromString)
}
//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
//If json is .Dictionary
for (key,subJson):(String, JSON) in json {
//Do something you want
}
第一个元素总是 String,即使 JSON 是一个数组
//If json is .Array
//The `index` is 0..<json.count's string value
for (index,subJson):(String, JSON) in json {
//Do something you want
}
使用下标来获取/设置数组或字典中的值
如果 JSON 是
nil
,但没有原因。这在 SwiftyJSON 中永远不会发生。
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"])
}
...
非可选 getter 被命名为 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
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]
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
}
//shows you whether value specified in JSON or not
if json["name"].isExists()
有关字面量可转换的更多信息:Swift 字面量可转换
//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"
SwiftyJSON 很好地封装了 Alamofire JSON 响应处理程序的结果
Alamofire.request(.GET, url).validate().responseJSON { response in
switch response.result {
case .Success:
if let value = response.result.value {
let json = JSON(value)
print("JSON: \(json)")
}
case .Failure(let error):
print(error)
}
}