How to access dictionary data outside its method on Swift? - ios

Question

I am creating a weather app with Swift. So I have retrieved the JSON data and stored it in a dictionary:
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()
I have used a Struct, in a difirent file, in order to organize and initialize the dictionary's data:
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
}
Now, I am implementing a chart for it. So I need to access the values from the dictionary in order to implement them on the chart. However, I've been unsuccessfull after many attemps.
The code lets me access the hourlyData struct, but not the weatherDictionary, since it was declared inside the session declaration.
Anyone knows an effective way to do it?
Any tips would be appreciated, thanks.

Answer 1

Try this for asynchronous request:
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!)
}
}
})
Not tested, but should work.

Answer 2

You need to use if let to parse dictionary.

Answer 3

Alright, so after the answers you guys posted I've updated the code a little. This is how the viewDidLoad looks like:
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)
}
}
})
And this is how the other swift file with the Struct looks like:
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)
}
}
Now the code looks fine, and it does not show any error, besides a warning under the 'if let', which says: Conditional cast from 'NSDictionary' to 'NSDictionary' always succeeds.
When I run the simulator, it crashes and displays: fatal error: unexpectedly found nil while unwrapping an Optional value. Highlighting, in green, the code line: daylyPop0 = weatherDictionary["hourly10_pop"] as! Int