Downloading and parsing json in swift

Question

I\'m trying to get the JSON from a website and parse it before putting it inside of an iOS view.

Here\'s my code;

func startConnection(){
        le         


        

Answer 1

The example below sends a request to fetch stock information - it's a bit more comprehensive, but has more cleanup and structure:

import Foundation

private let kSNStockInfoFetchRequestPath:String = "http://dev.markitondemand.com/Api/v2/Quote/json"

private func SNStockInfoFetchRequestURL(symbol:String) -> NSURL? {
  if let components:NSURLComponents = NSURLComponents(string:kSNStockInfoFetchRequestPath) {
    components.queryItems = [NSURLQueryItem(name:"symbol", value:symbol)]
    return components.URL
  }
  return nil
}

private func SNStockInfoFetchRequestURLRequest(symbol:String) ->  NSURLRequest? {
  if let requestURL:NSURL = SNStockInfoFetchRequestURL(symbol) {
    var request:NSMutableURLRequest = NSMutableURLRequest(URL:requestURL)
    request.HTTPMethod = "GET"
    return request
  }
  return nil
}

private func SNStockInfoFetchRequestParseData(receivedData:NSData, error:NSErrorPointer) -> NSDictionary? {
  return NSJSONSerialization.JSONObjectWithData(receivedData, options:NSJSONReadingOptions.MutableContainers, error:error) as? NSDictionary
}

class SNStockInfoFetchRequest: NSObject,
NSURLConnectionDataDelegate
{
  private let symbol:String
  private (set) var fetching:Bool
  private lazy var receivedData = NSMutableData()

  init(symbol:String) {
    self.symbol = symbol
    self.fetching = false
  }

  func start() {
    assert(!fetching, "Should not start a request that has already started!")
    fetching = true
    if let request:NSURLRequest = SNStockInfoFetchRequestURLRequest(symbol) {
      var connection:NSURLConnection = NSURLConnection(request:request, delegate:self, startImmediately:true)!
      connection.start()
    }
  }

  // MARK: NSURLConnectionDataDelegate

  func connection(connection:NSURLConnection, didReceiveData data:NSData) {
    assert(fetching, "Should only receive data while activly fetching!")
    self.receivedData.appendData(data)
  }

  func connectionDidFinishLoading(connection:NSURLConnection) {
    var error:NSError?
    if let result:NSDictionary = SNStockInfoFetchRequestParseData(receivedData, &error) {
      println(result)
    } else {
      println(error)
    }

  }
}

We can now use the request as such:

let fetcher:SNStockInfoFetchRequest = SNStockInfoFetchRequest(symbol:"MSFT")
fetcher.start()

This should output the JSON in case of a success, or the error in case of a failure. Hope this helps! If you use the same structure, make sure to use a delegate to either return the parsed JSON (or even better, an immutable value object) or indicate a failure.

Answer 2

These two functions worked for me:

    func getJSON(urlToRequest: String) -> NSData{
        return NSData(contentsOfURL: NSURL(string: urlToRequest))
    }

    func parseJSON(inputData: NSData) -> NSDictionary{
        var error: NSError?
        var boardsDictionary: NSDictionary = NSJSONSerialization.JSONObjectWithData(inputData, options: NSJSONReadingOptions.MutableContainers, error: &error) as NSDictionary

        return boardsDictionary
    }

Answer 3

//
//  ViewController.swift
//  Test2
//
//  Created by fingent on 11/08/15.
//  Copyright (c) 2015 fingent. All rights reserved.
//

import UIKit

class ViewController: UIViewController,NSURLConnectionDelegate

{
lazy var data = NSMutableData()

    @IBAction func t1(sender: AnyObject) {
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        startConnection()

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func startConnection(){
        let urlPath: String = "https://api.github.com/users/mralexgray"
        var url: NSURL = NSURL(string: urlPath)!
        var request: NSURLRequest = NSURLRequest(URL: url)
        var connection: NSURLConnection = NSURLConnection(request: request, delegate: self, startImmediately: false)!
        connection.start()
    }

    func connection(connection: NSURLConnection!, didReceiveData data: NSData!){
        self.data.appendData(data)
    }

    func buttonAction(sender: UIButton!){
        startConnection()
    }

    func connectionDidFinishLoading(connection: NSURLConnection!) {
        var err: NSError
        // throwing an error on the line below (can't figure out where the error message is)
        var jsonResult: NSDictionary = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as NSDictionary
        println(jsonResult)
    }


}