Swift-JS交互样例

# SwiftyJSON [](https://travis-ci.org/SwiftyJSON/SwiftyJSON) [](https://github.com/Carthage/Carthage)   SwiftyJSON makes it easy to deal with JSON data in Swift. 1. [Why is the typical JSON handling in Swift NOT good](#why-is-the-typical-json-handling-in-swift-not-good) 2. [Requirements](#requirements) 3. [Integration](#integration) 4. [Usage](#usage) - [Initialization](#initialization) - [Subscript](#subscript) - [Loop](#loop) - [Error](#error) - [Optional getter](#optional-getter) - [Non-optional getter](#non-optional-getter) - [Setter](#setter) - [Raw object](#raw-object) - [Literal convertibles](#literal-convertibles) - [Merging](#merging) 5. [Work with Alamofire](#work-with-alamofire) > For Legacy Swift support, take a look at the [swift2 branch](https://github.com/SwiftyJSON/SwiftyJSON/tree/swift2) > [中文介绍](http://tangplin.github.io/swiftyjson/) ## 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: ```swift 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: ```swift 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: ```swift 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. ```swift 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"]) } ``` ## 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](http://cocoapods.org/) to install `SwiftyJSON`by adding it to your `Podfile`: ```ruby 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: #### Carthage (iOS 8+, OS X 10.9+) You can use [Carthage](https://github.com/Carthage/Carthage) to install `SwiftyJSON` by adding it to your `Cartfile`: ``` github "SwiftyJSON/SwiftyJSON" ``` #### Swift Package Manager You can use [The Swift Package Manager](https://swift.org/package-manager) to install `SwiftyJSON` by adding the proper description to your `Package.swift` file: ```swift 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](https://swift.org/package-manager) is still in early design and development, for more information checkout its [GitHub Page](https://github.com/apple/swift-package-manager) #### 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 ```swift import SwiftyJSON ``` ```swift let json = JSON(data: dataFromNetworking) ``` ```swift let json = JSON(jsonObject) ``` ```swift if let dataFromString = jsonString.data(using: .utf8, allowLossyConversion: false) { let json = JSON(data: dataFromString) } ``` #### Subscript ```swift //Getting a double from a JSON Array let name = json[0].double ``` ```swift //Getting an array of string from a JSON Array let arrayNames = json["users"].arrayValue.map({$0["name"].stringValue}) ``` ```swift //Getting a string from a JSON Dictionary let name = json["name"].stringValue ``` ```swift //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 ``` ```swift //With a hard way let name = json[].string ``` ```swift //With a custom way let keys:[SubscriptType] = [1,"list",2,"name"] let name = json[keys].string ``` #### Loop ```swift //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* ```swift //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. ```swift 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" } ``` ```swift 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" } ``` ```swift 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" } ``` #### Optional getter ```swift //NSNumber if let id = json["user"]["favourites_count"].number { //Do something you want } else { //Print the error print(json["user"]["favourites_count"].error) } ``` ```swift //String if let id = json["user"]["name"].string { //Do something you want } else { //Print the error print(json["user"]["name"]) } ``` ```swift //Bool if let id = json["user"]["is_translator"].bool { //Do something you want } else { //Print the error print(json["user"]["is_translator"]) } ``` ```swift //Int if let 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` ```swift //If not a Number or nil, return 0 let id: Int = json["id"].intValue ``` ```swift //If not a String or nil, return