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  • 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
    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:

    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 SwiftyJSONby 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:

    1. for Projects, just drag SwiftyJSON.swift to the project tree
    2. 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
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  • 原文地址:https://www.cnblogs.com/cmblogs/p/4552439.html
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