例如,假设从服务器返回的JSON是：

{     
 "data":{  
     "id":"92","name":"harry","username":"Hazza"
   },"error":false
}

我想获取用户名字符串,所以为此我使用以下方法获取数据对象：

let data = json["data"].dictionaryValue

然后为了获取我希望能够做的用户名字符串

let username = data["username"].stringValue

但是,这会返回一个错误,说'(String,JSON)没有名为’.stringValue’的成员.

这个看似简单的问题在哪里出错了？

谢谢.

if let username = json["data"]["username"].string {
    println(username)
}

数据是与Alamofire下载的,它很好地工作,但用SwiftyJson解析json是非常慢的.为了看看图书馆真的是这个问题,我重写了在解析数据的许多地方之一的json解析.在下面的代码中,我解析了约400个旅游景点之一的开放时间.

看到这些截图的差异,7,7秒到185毫秒：

快乐的方式：

let openDescription:String = json["openingHours"]["openingHoursGenericExceptions"].string!
    let monopen:[String]    = json["openingHours"]["Monday"]["From"].string!.componentsSeparatedByString(":")
    let monClose:[String]   = json["openingHours"]["Monday"]["To"].string!.componentsSeparatedByString(":")
    let tueOpen:[String]    = json["openingHours"]["Tuesday"]["From"].string!.componentsSeparatedByString(":")
    let tueClose:[String]   = json["openingHours"]["Tuesday"]["To"].string!.componentsSeparatedByString(":")
    let wedOpen:[String]    = json["openingHours"]["Wednesday"]["From"].string!.componentsSeparatedByString(":")
    let wedClose:[String]   = json["openingHours"]["Wednesday"]["To"].string!.componentsSeparatedByString(":")
    let thuOpen:[String]    = json["openingHours"]["Thursday"]["From"].string!.componentsSeparatedByString(":")
    let thuClose:[String]   = json["openingHours"]["Thursday"]["To"].string!.componentsSeparatedByString(":")
    let friOpen:[String]    = json["openingHours"]["Friday"]["From"].string!.componentsSeparatedByString(":")
    let friClose:[String]   = json["openingHours"]["Friday"]["To"].string!.componentsSeparatedByString(":")
    let satOpen:[String]    = json["openingHours"]["Saturday"]["From"].string!.componentsSeparatedByString(":")
    let satClose:[String]   = json["openingHours"]["Saturday"]["To"].string!.componentsSeparatedByString(":")
    let sunopen:[String]    = json["openingHours"]["Sunday"]["From"].string!.componentsSeparatedByString(":")
    let sunClose:[String]   = json["openingHours"]["Sunday"]["To"].string!.componentsSeparatedByString(":")

本土方式：

var monopen:[String] = []
    var monClose:[String] = []
    var tueOpen:[String] = []
    var tueClose:[String] = []
    var wedOpen:[String] = []
    var wedClose:[String] = []
    var thuOpen:[String] = []
    var thuClose:[String] = []
    var friOpen:[String] = []
    var friClose:[String] = []
    var satOpen:[String] = []
    var satClose:[String] = []
    var sunopen:[String] = []
    var sunClose:[String] = []
    var openDescription:String = ""

    if let attractionsArray = orgJson as? NSArray{
        if let attraction = attractionsArray[0] as? NSDictionary{
            if let openHours = attraction["openingHours"] as? NSDictionary{
                if let day = openHours["Monday"] as? NSDictionary{
                    if let open = day["From"] as? String{
                        monopen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"] as? String{
                        monClose = close.componentsSeparatedByString(":")
                    }
                }
                if let day = openHours["Tuesday"] as? NSDictionary{
                    if let open = day["From"] as? String{
                        tueOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"] as? String{
                        tueClose = close.componentsSeparatedByString(":")
                    }
                }
                if let day = openHours["Wednesday"] as? NSDictionary{
                    if let open = day["From"] as? String{
                        wedOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"] as? String{
                        wedClose = close.componentsSeparatedByString(":")
                    }
                }
                if let day = openHours["Thursday"] as? NSDictionary{
                    if let open = day["From"] as? String{
                        thuOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"] as? String{
                        thuClose = close.componentsSeparatedByString(":")
                    }
                }
                if let day = openHours["Friday"] as? NSDictionary{
                    if let open = day["From"] as? String{
                        friOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"] as? String{
                        friClose = close.componentsSeparatedByString(":")
                    }
                }
                if let day = openHours["Saturday"] as? NSDictionary{
                    if let open = day["From"] as? String{
                        satOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"] as? String{
                        satClose = close.componentsSeparatedByString(":")
                    }
                }
                if let day = openHours["Sunday"] as? NSDictionary{
                    if let open = day["From"] as? String{
                        sunopen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"] as? String{
                        sunClose = close.componentsSeparatedByString(":")
                    }
                }
                if let desc = openHours["openingHoursGenericExceptions"] as? String{
                    openDescription = desc
                }
            }
        }
    }

这只是要解析的数据的一部分,因此该应用程序中的性能非常明显.

我猜问题是,我使用SwiftyJSON不正确或者这是预期的吗？

SwiftyJSON版本有45个下标访问,但本机只有23个下标访问.

要使“本土方式”相当,应该是这样的：

let openDescription = attraction["openingHours"]!["openingHoursGenericExceptions"] as String
let monopen  = (attraction["openingHours"]!["Monday"]!!["From"] as String).componentsSeparatedByString(":")
let monClose = (attraction["openingHours"]!["Monday"]!!["To"] as String).componentsSeparatedByString(":")
let tueOpen  = (attraction["openingHours"]!["Tuesday"]!!["From"] as String).componentsSeparatedByString(":")
let tueClose = (attraction["openingHours"]!["Tuesday"]!!["To"]! as String).componentsSeparatedByString(":")
// ...

或“快乐的方式”应该是：

let openHours = json[0]["openingHours"]
var day:JSON

day = openHours["Monday"]
if let open = day["From"].string {
    monopen = open.componentsSeparatedByString(":")
}
if let close = day["To"].string {
    monClose = close.componentsSeparatedByString(":")
}
day = openHours["Tuesday"]
if let open = day["From"].string {
    tueOpen = open.componentsSeparatedByString(":")
}
if let close = day["To"].string {
    tueClose = close.componentsSeparatedByString(":")
}
// ...

无论如何,是的,SwiftyJSON很慢.我们来衡量：

import Foundation
import XCTest

let orgJson:AnyObject = [
    [
        "openingHours": [
            "openingHoursGenericExceptions": "test","Monday":    ["From":"1:2:3","To":"1:2:3"],"Tuesday":   ["From":"1:2:3","Wednesday": ["From":"1:2:3","Thursday":  ["From":"1:2:3","Friday":    ["From":"1:2:3","Saturday":  ["From":"1:2:3","Sunday":    ["From":"1:2:3",]
    ]
]
let json = JSON(orgJson)

class JSONTestTests: XCTestCase {

    func testNativeSubscript() {
        measureBlock { () -> Void in

            for _ in 0 ..< 400 {
                autoreleasepool {
                    if let attraction = orgJson[0] as? NSDictionary {
                        let openDescription = attraction["openingHours"]!["openingHoursGenericExceptions"] as String
                        let monopen  = (attraction["openingHours"]!["Monday"]!!["From"] as String).componentsSeparatedByString(":")
                        let monClose = (attraction["openingHours"]!["Monday"]!!["To"] as String).componentsSeparatedByString(":")
                        let tueOpen  = (attraction["openingHours"]!["Tuesday"]!!["From"] as String).componentsSeparatedByString(":")
                        let tueClose = (attraction["openingHours"]!["Tuesday"]!!["To"] as String).componentsSeparatedByString(":")
                        let wedOpen  = (attraction["openingHours"]!["Wednesday"]!!["From"] as String).componentsSeparatedByString(":")
                        let wedClose = (attraction["openingHours"]!["Wednesday"]!!["To"] as String).componentsSeparatedByString(":")
                        let thuOpen  = (attraction["openingHours"]!["Thursday"]!!["From"] as String).componentsSeparatedByString(":")
                        let thuClose = (attraction["openingHours"]!["Thursday"]!!["To"] as String).componentsSeparatedByString(":")
                        let friOpen  = (attraction["openingHours"]!["Friday"]!!["From"] as String).componentsSeparatedByString(":")
                        let friClose = (attraction["openingHours"]!["Friday"]!!["To"] as String).componentsSeparatedByString(":")
                        let satOpen  = (attraction["openingHours"]!["Saturday"]!!["From"] as String).componentsSeparatedByString(":")
                        let satClose = (attraction["openingHours"]!["Saturday"]!!["To"] as String).componentsSeparatedByString(":")
                        let sunopen  = (attraction["openingHours"]!["Sunday"]!!["From"] as String).componentsSeparatedByString(":")
                        let sunClose = (attraction["openingHours"]!["Sunday"]!!["To"] as String).componentsSeparatedByString(":")
                        XCTAssertEqual(monopen,["1","2","3"],"")
                        XCTAssertEqual(openDescription,"test")
                    }
                }
            }
        }
    }

    func testJSONSubscript() {
        measureBlock { () -> Void in
            for _ in 0 ..< 400 {
                autoreleasepool {
                    let attraction = json[0]
                    let openDescription:String = attraction["openingHours"]["openingHoursGenericExceptions"].string!
                    let monopen:[String]    = attraction["openingHours"]["Monday"]["From"].string!.componentsSeparatedByString(":")
                    let monClose:[String]   = attraction["openingHours"]["Monday"]["To"].string!.componentsSeparatedByString(":")
                    let tueOpen:[String]    = attraction["openingHours"]["Tuesday"]["From"].string!.componentsSeparatedByString(":")
                    let tueClose:[String]   = attraction["openingHours"]["Tuesday"]["To"].string!.componentsSeparatedByString(":")
                    let wedOpen:[String]    = attraction["openingHours"]["Wednesday"]["From"].string!.componentsSeparatedByString(":")
                    let wedClose:[String]   = attraction["openingHours"]["Wednesday"]["To"].string!.componentsSeparatedByString(":")
                    let thuOpen:[String]    = attraction["openingHours"]["Thursday"]["From"].string!.componentsSeparatedByString(":")
                    let thuClose:[String]   = attraction["openingHours"]["Thursday"]["To"].string!.componentsSeparatedByString(":")
                    let friOpen:[String]    = attraction["openingHours"]["Friday"]["From"].string!.componentsSeparatedByString(":")
                    let friClose:[String]   = attraction["openingHours"]["Friday"]["To"].string!.componentsSeparatedByString(":")
                    let satOpen:[String]    = attraction["openingHours"]["Saturday"]["From"].string!.componentsSeparatedByString(":")
                    let satClose:[String]   = attraction["openingHours"]["Saturday"]["To"].string!.componentsSeparatedByString(":")
                    let sunopen:[String]    = attraction["openingHours"]["Sunday"]["From"].string!.componentsSeparatedByString(":")
                    let sunClose:[String]   = attraction["openingHours"]["Sunday"]["To"].string!.componentsSeparatedByString(":")
                    XCTAssertEqual(monopen,"")
                }
            }
        }
    }

    func testNativeBinding() {
        measureBlock { () -> Void in
            for _ in 0 ..< 400 {
                autoreleasepool {
                    var monopen:[String] = []
                    var monClose:[String] = []
                    var tueOpen:[String] = []
                    var tueClose:[String] = []
                    var wedOpen:[String] = []
                    var wedClose:[String] = []
                    var thuOpen:[String] = []
                    var thuClose:[String] = []
                    var friOpen:[String] = []
                    var friClose:[String] = []
                    var satOpen:[String] = []
                    var satClose:[String] = []
                    var sunopen:[String] = []
                    var sunClose:[String] = []
                    var openDescription:String = ""

                    if let attractionsArray = orgJson as? NSArray{
                        if let attraction = attractionsArray[0] as? NSDictionary{
                            if let openHours = attraction["openingHours"] as? NSDictionary{
                                if let day = openHours["Monday"] as? NSDictionary{
                                    if let open = day["From"] as? String{
                                        monopen = open.componentsSeparatedByString(":")
                                    }
                                    if let close = day["To"] as? String{
                                        monClose = close.componentsSeparatedByString(":")
                                    }
                                }
                                if let day = openHours["Tuesday"] as? NSDictionary{
                                    if let open = day["From"] as? String{
                                        tueOpen = open.componentsSeparatedByString(":")
                                    }
                                    if let close = day["To"] as? String{
                                        tueClose = close.componentsSeparatedByString(":")
                                    }
                                }
                                if let day = openHours["Wednesday"] as? NSDictionary{
                                    if let open = day["From"] as? String{
                                        wedOpen = open.componentsSeparatedByString(":")
                                    }
                                    if let close = day["To"] as? String{
                                        wedClose = close.componentsSeparatedByString(":")
                                    }
                                }
                                if let day = openHours["Thursday"] as? NSDictionary{
                                    if let open = day["From"] as? String{
                                        thuOpen = open.componentsSeparatedByString(":")
                                    }
                                    if let close = day["To"] as? String{
                                        thuClose = close.componentsSeparatedByString(":")
                                    }
                                }
                                if let day = openHours["Friday"] as? NSDictionary{
                                    if let open = day["From"] as? String{
                                        friOpen = open.componentsSeparatedByString(":")
                                    }
                                    if let close = day["To"] as? String{
                                        friClose = close.componentsSeparatedByString(":")
                                    }
                                }
                                if let day = openHours["Saturday"] as? NSDictionary{
                                    if let open = day["From"] as? String{
                                        satOpen = open.componentsSeparatedByString(":")
                                    }
                                    if let close = day["To"] as? String{
                                        satClose = close.componentsSeparatedByString(":")
                                    }
                                }
                                if let day = openHours["Sunday"] as? NSDictionary{
                                    if let open = day["From"] as? String{
                                        sunopen = open.componentsSeparatedByString(":")
                                    }
                                    if let close = day["To"] as? String{
                                        sunClose = close.componentsSeparatedByString(":")
                                    }
                                }
                                if let desc = openHours["openingHoursGenericExceptions"] as? String{
                                    openDescription = desc
                                }
                            }
                        }
                    }
                    XCTAssertEqual(monopen,"")
                }
            }
        }
    }
    func testJSONBinding() {
        measureBlock { () -> Void in
            for _ in 0 ..< 400 {
                autoreleasepool {
                    var monopen:[String] = []
                    var monClose:[String] = []
                    var tueOpen:[String] = []
                    var tueClose:[String] = []
                    var wedOpen:[String] = []
                    var wedClose:[String] = []
                    var thuOpen:[String] = []
                    var thuClose:[String] = []
                    var friOpen:[String] = []
                    var friClose:[String] = []
                    var satOpen:[String] = []
                    var satClose:[String] = []
                    var sunopen:[String] = []
                    var sunClose:[String] = []
                    var openDescription:String = ""

                    let openHours = json[0]["openingHours"]
                    var day:JSON

                    day = openHours["Monday"]
                    if let open = day["From"].string {
                        monopen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"].string {
                        monClose
                            = close.componentsSeparatedByString(":")
                    }
                    day = openHours["Tuesday"]
                    if let open = day["From"].string {
                        tueOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"].string {
                        tueClose = close.componentsSeparatedByString(":")
                    }
                    day = openHours["WednesDay"]
                    if let open = day["From"].string {
                        wedOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"].string {
                        wedClose = close.componentsSeparatedByString(":")
                    }
                    day = openHours["Thursday"]
                    if let open = day["From"].string {
                        thuOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"].string {
                        thuClose = close.componentsSeparatedByString(":")
                    }
                    day = openHours["Friday"]
                    if let open = day["From"].string {
                        friOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"].string {
                        friClose = close.componentsSeparatedByString(":")
                    }
                    day = openHours["Saturday"]
                    if let open = day["From"].string {
                        satOpen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"].string {
                        satClose = close.componentsSeparatedByString(":")
                    }
                    day = openHours["Sunday"]
                    if let open = day["From"].string {
                        sunopen = open.componentsSeparatedByString(":")
                    }
                    if let close = day["To"].string {
                        sunClose = close.componentsSeparatedByString(":")
                    }
                    XCTAssertEqual(monopen,"")
                }
            }
        }
    }

}

输出：

<unkNown>:0: Test Case '-[JSONTestTests.JSONTestTests testJSONBinding]' measured [Time,seconds] average: 0.804,relative standard deviation: 5.592%,values: [0.835687,0.814827,0.819685,0.841900,0.764961,0.845202,0.691442,0.779255,0.818213,0.830698],performanceMetricID:com.apple.XCTPerformanceMetric_WallClockTime,baselineName: "",baselineAverage:,maxPercentRegression: 10.000%,maxPercentRelativeStandardDeviation: 10.000%,maxRegression: 0.100,maxStandardDeviation: 0.100
<unkNown>:0: Test Case '-[JSONTestTests.JSONTestTests testJSONSubscript]' measured [Time,seconds] average: 4.247,relative standard deviation: 3.496%,values: [4.019640,4.004123,4.146146,4.194535,4.487171,4.300971,4.310613,4.408405,4.318354,4.279362],maxStandardDeviation: 0.100
<unkNown>:0: Test Case '-[JSONTestTests.JSONTestTests testNativeBinding]' measured [Time,seconds] average: 0.223,relative standard deviation: 2.773%,values: [0.221099,0.227395,0.218860,0.225989,0.227128,0.222370,0.229956,0.214535,0.210818,0.229868],maxStandardDeviation: 0.100
<unkNown>:0: Test Case '-[JSONTestTests.JSONTestTests testNativeSubscript]' measured [Time,seconds] average: 0.362,relative standard deviation: 17.528%,values: [0.346285,0.316185,0.333650,0.339416,0.330243,0.354034,0.378730,0.269519,0.486904,0.467607],maxStandardDeviation: 0.100

>你的SwiftyJSON：4.247
>您的母语：0.223
>我的SwiftyJSON：0.804
>我的母语：0.362

顺便说一下,如果我是你,我会做一些像：

if let hours = orgJson[0]?["openingHours"] as? NSDictionary {
    let openDescription = hours["openingHoursGenericExceptions"] as? String ?? ""
    let monopen  = hours["Monday"]?["From"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let monClose = hours["Monday"]?["To"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let tueOpen  = hours["Tuesday"]?["From"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let tueClose = hours["Tuesday"]?["To"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let wedOpen  = hours["Wednesday"]?["From"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let wedClose = hours["Wednesday"]?["To"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let thuOpen  = hours["Thursday"]?["From"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let thuClose = hours["Thursday"]?["To"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let friOpen  = hours["Friday"]?["From"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let friClose = hours["Friday"]?["To"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let satOpen  = hours["Saturday"]?["From"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let satClose = hours["Saturday"]?["To"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let sunopen  = hours["Sunday"]?["From"]??.componentsSeparatedByString?(":") as? [String] ?? []
    let sunClose = hours["Sunday"]?["To"]??.componentsSeparatedByString?(":") as? [String] ?? []

    // ...
}

它是相当快,安全,不那么复杂.

为什么SwiftyJSON慢？

在下标访问中,SwiftyJSON确实：

>检查键是String
>下标再次与self [key：sub]
>检查底层对象是NSDictionary
>下标底层的NSDictionary与提供的键
>使用结果构造JSON对象
>返回

也许编译器优化了一些步骤,但是“比本机慢”有些不可避免的:)

我使用Alamofire和SwiftyJSON,我的JSON数据看起来像这样：

{
  "528" : {
    "name" : "Name 1","id" : "528","product_id" : null,"visible" : "0","level" : "2"
  },"29" : {
    "name" : "Name 2","id" : "29","visible" : "1","level" : "1"
  },"173" : {
    "name" : "Name 3","id" : "173","143" : {
    "name" : "Name 4","id" : "143",

…使用此代码：

Alamofire.request(.GET,dataURL,parameters: nil,encoding: .JSON)

    .responseJSON { (request,response,jsonData,error) in

        let json = JSON(jsonData!) 

        println(json)

    }

…所以JSON一切都应该没问题

>我如何访问该数据？我的意思是我如何获得名称,ID,product_ids等
>我如何将该数据(名称)放入我的TableViewController？

>创建一个名为APIProtocol的协议.
>使用GET方法设置API类,该方法接受APIProtocol类型的委托.
>设置TableViewController以实现APIProtocol.
>从TableViewController调用API.get()

码

// Step 1
protocol APIProtocol {
  func didReceiveResult(results: JSON)
}

// Step 2
func get(path: String,parameters: [String: AnyObject]? = nil,delegate: APIProtocol? = nil){
  let url = "\(self.hostname)\(path)"
  NSLog("Preparing for GET request to: \(url)")

  Alamofire.request(.GET,url,parameters: parameters)
    .responseJSON { (req,res,json,error) in
      if(error != nil) {
        NSLog("GET Error: \(error)")
        println(res)
      }
      else {
        var json = JSON(json!)
        NSLog("GET Result: \(json)")

        // Call delegate if it was passed into the call
        if(delegate != nil) {
            delegate!.didReceiveResult(json)
        }
      }
    }
}

// Step 3
class ActivityViewController: UITableViewController,APIProtocol {
  var activityModelList: NSMutableArray = [] // This is the array that my tableView is using.

  ... 

  func didReceiveResult(result: JSON) {
    var activities: NSMutableArray = []

    NSLog("Activity.didReceiveResult: \(result)")

    for (index: String,activity: JSON) in result {

      var activityModel = ActivityModel(
        id: activity["id"].intValue,message: activity["message"].stringValue
      )

      activities.addobject(activityModel)
    }

    // Set our array of new models
    activityModelList = activities

    // Make sure we are on the main thread,and update the UI.
    dispatch_sync(dispatch_get_main_queue(),{
      self.refreshControl!.endRefreshing()
      self.tableView.reloadData()
    })
  }
}

// Step 4
override func viewDidLoad() {
  MyAPI.get("/activities",delegate: self)
}