Question

我正在使用Swift创建一个天气应用程序。所以我检索了JSON数据并将其存储在字典中：

import UIKit

class ViewController: UIViewController {


override func viewDidLoad() {
    super.viewDidLoad()

    ///////getting URL:

    let mainAddress = NSURL(string: "https://...") //for NY



    //Now, getting the data syncronously by creating a session object::
    let sharedSession = NSURLSession.sharedSession()
    let downloadTask: NSURLSessionDownloadTask =
    sharedSession.downloadTaskWithURL(mainAddress!, completionHandler: {
        (location:NSURL!, response:NSURLResponse!, error: NSError!) -> Void in



        //using the if statement to avoid crashing when the URL is wrong.
        if error == nil {
            //Now, creating a dataObject for the task:
            let dataObject = NSData(contentsOfURL: location)
            //getting a formated dictionary of the data from URL:
            let weatherDictionary: NSDictionary = NSJSONSerialization.JSONObjectWithData(dataObject!, options: nil, error: nil) as NSDictionary //added '!' to NSdata for now

        }




    })

    downloadTask.resume()

我在diffirent文件中使用了一个Struct，以便组织和初始化字典的数据：

import Foundation
import UIKit
import WatchKit
//created the struct just to better organize the data. In the future, if the API keys change, it would be easier to ajust the code, rather than if the data was directly read from the API onto the graph.

struct hourlyData {


///declaring only keys that have Integers as value.
var daylyPop0 : Int
var daylyPop1 : Int
var daylyPop2 : Int
var daylyPop3 : Int
var daylyPop4 : Int



var summaryNowDay : String
var summaryNowNight : String
var iconNow : String
var currentTime: String?

//Initializing the values here. With optional properties:
init(weatherDictionary:NSDictionary){

    daylyPop0 = weatherDictionary["daily0_pop"] as Int
    daylyPop1 = weatherDictionary["daily1_pop"] as Int
    daylyPop2 = weatherDictionary["daily4_pop"] as Int
    daylyPop3 = weatherDictionary["daily3_pop"] as Int
    daylyPop4 = weatherDictionary["daily2_pop"] as Int

}

现在，我正在为它实现一个图表。所以我需要访问字典中的值才能在图表上实现它们。但是，经过多次尝试后，我都没有成功。代码允许我访问hourlyData结构，但不访问weatherDictionary，因为它是在会话声明中声明的。

任何人都知道有效的方法吗？

任何提示都将不胜感激，谢谢。

Answer 1

您需要使用 if 来解析字典。

Answer 2

尝试使用异步请求：

var request = NSURLRequest(URL: url)
var dict = NSDictionary()

var yourSavedData = hourlyData()

NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue()) { (response, data, error) -> Void in

    if data == nil
    {
        println("Error in connection")
        return
    }

    var error = NSErrorPointer()
    dict = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: error) as NSDictionary

    if error != nil
    {
        println(error.debugDescription)
        return
    }

    NSOperationQueue.mainQueue().addOperationWithBlock({ () -> Void in


            if let yourDict = dict as? NSDictionary
            {
                yourSavedData = hourlyData(yourDict!)
            }

        }

    })

未经测试，但应该可以使用。

Answer 3

好吧，所以在你们发布答案后，我们已经更新了一些代码。这就是viewDidLoad的样子：

override func viewDidLoad() {
    super.viewDidLoad()

    ///////getting URL:

    let url = NSURL(string: "http://..........") //for NY
    var request = NSURLRequest(URL: url!)
    var dict = NSDictionary()

    var yourSavedData = hourlyData(weatherDictionary: NSDictionary())

    NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue()) { (response, data, error) -> Void in

        if data == nil
        {
            println("Error in connection")
            return
        }

        var error = NSErrorPointer()
        dict = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: error) as! NSDictionary

        if error != nil
        {
            println(error.debugDescription)
            return
        }

        NSOperationQueue.mainQueue().addOperationWithBlock({ () -> Void in


            if let yourDict = dict as? NSDictionary
            {
                yourSavedData = hourlyData(weatherDictionary: yourDict)
            }

        }

    })

这就是带有Struct的其他swift文件的样子：

struct hourlyData {


///declaring only keys that have Integers as value.
var daylyPop0 : Int
var daylyPop1 : Int
var daylyPop2 : Int
var daylyPop3 : Int
var daylyPop4 : Int



var summaryNowDay : String
var summaryNowNight : String
var iconNow : String
var currentTime: String?

//Initializing the values here. With optional properties:
init(weatherDictionary:NSDictionary){

    daylyPop0 = weatherDictionary["hourly10_pop"] as! Int
    daylyPop1 = weatherDictionary["hourly11_pop"] as! Int
    daylyPop2 = weatherDictionary["hourly12_pop"] as! Int
    daylyPop3 = weatherDictionary["hourly13_pop"] as! Int
    daylyPop4 = weatherDictionary["hourly14_pop"] as! Int



    summaryNowDay = weatherDictionary["today_day_fcttext_metric"] as! String
    summaryNowNight = weatherDictionary["today_night_fcttext_metric"] as! String

    iconNow = weatherDictionary["current_icon"] as! String

    let currentTimeIntValue = weatherDictionary["forecast_time"] as! Int
    currentTime = dateStringFromUnixTime(currentTimeIntValue)


}

//Converting unixTime to a desired style:::used ShortStyle in this case:
func dateStringFromUnixTime(unixTime: Int) -> String{

    let timeInSeconds = NSTimeInterval(unixTime)

    let weatherDate = NSDate(timeIntervalSince1970: timeInSeconds)

    let dateFormatter = NSDateFormatter()
    dateFormatter.timeStyle = .ShortStyle

    return dateFormatter.stringFromDate(weatherDate)

}

}

现在代码看起来很好，并且没有显示任何错误，除了在＆＃39; if let＆＃39;下面的警告，其中说：来自＆NSCictionary＆＃39;的条件演员。来自NSDictionary＆＃39;永远成功。当我运行模拟器时，它会崩溃并显示：致命错误：在展开Optional值时意外发现nil。以绿色突出显示代码行：daylyPop0 = weatherDictionary [＆＃34; hourly10_pop＆＃34;] as！ INT

如何在Swift上的方法之外访问字典数据？

3 个答案: