title: URLSession.dataTask return the data with 0
body: <p>I have a web page for giving me the server data in JSON format and I am trying to to reach the site and get these objects. But the data will return with 0; empty variable. My code like this.</p>
  
  <pre><code>    func downloadItems() {
  
      let url: URL = URL(string: urlPath)!
  
      let defaultSession = URLSession(configuration: URLSessionConfiguration.default)
  
      let task = defaultSession.dataTask(with: url) {
          (data, response, error) in
  
          if error != nil {
              print("Failed to download data")
          }else {
              let httpResponse = response as? HTTPURLResponse
              print("data is like: \(data as! NSData)")
              print(httpResponse)
              self.data = data!
              print("Data downloaded")
              self.parseJSON(self.data)
          }
  
      }
  
      task.resume()
  }
  
  func parseJSON(_ data: Data){
      var jsonResult = NSArray()
  
      do{
          jsonResult = try JSONSerialization.jsonObject(with: data, options: []) as! NSArray
          print(jsonResult)
      } catch let error as NSError {
          print(error)
      }
  
      var jsonElement = NSDictionary()
      let forest = NSMutableArray()
  
      for tree in 0 ..&lt; jsonResult.count {
  
          jsonElement = jsonResult[tree] as! NSDictionary
  
          let tempTree = trees()
  
          if let latinName = jsonElement["latin_name"] as? String,
          let turkishName = jsonElement["turkish_name"] as? String,
          let seedType = jsonElement["seed_type"] as? Int,
          let leafType = jsonElement["leaf_type"] as? Int,
          let spreadingArea = jsonElement["spreading_area"] as? String,
          let bothanicalProp = jsonElement["bothanical_prop"] as? String {
              tempTree.latin_name = latinName
              tempTree.turkish_name = turkishName
              tempTree.seed_type = seedType
              tempTree.leaf_type = leafType
              tempTree.spreading_area = spreadingArea
              tempTree.botanical_prop = bothanicalProp
          }
  
          forest.add(tempTree)
  
      }
  
      DispatchQueue.main.async {
          self.delegate.itemsDownloaded(items: forest)
      }
  
  }
  </code></pre>
  
  <p>and my main view controller is like that</p>
  
  <pre><code>    override func viewDidLoad() {
      super.viewDidLoad()
  
      //table view delegats and datasource declaration
      treeTableView.delegate = self
      treeTableView.dataSource = self
  
      let treeModel = trees()
      treeModel.delegate = self
      treeModel.downloadItems(completion: &lt;#T##(Data?) -&gt; Void#&gt;)
  
  }
  
  func itemsDownloaded(items: NSArray) {
      feedTrees = items
      self.treeTableView.reloadData()
  }
  </code></pre>
  
  <p>When I enter the site the JSON object is here. But when I tried to retrieve the object with dataTask. Data will be 0. Also HTTP Response is 200. Is there any knowledge about this situation ? Thanks and good coding.</p>
  
  <p>print(jsonResult) is</p>
  
  <pre><code>{
      "bothanical_prop" = "T\U00fcrkiyede park ve bah\U00e7elerde dekoratif ama\U00e7la kullan\U0131l\U0131r. Do\U011fal yay\U0131l\U0131\U015f alan\U0131 \U015eili'nin g\U00fcneyi ve G\U00fcnaybat\U0131 Arjantin'deki And Da\U011flar\U0131d\U0131r.";
      "latin_name" = "Araucaria araucana (Molina) K. Koch.";
      "leaf_type" = 1;
      "seed_type" = 1;
      "spreading_area" = "Do\U011fal alanlarda erkekler 15-18 m, di\U015filer ise 30-50 m ye kadar boylanabilir. Park ve bah\U00e7elerde ise 10 m'yi nadiren ge\U00e7en herdemye\U015fil a\U011fa\U00e7lard\U0131r. G\U00f6zvdesi d\U00fczg\U00fcnd\U00fcr; \U00f6zellikle gen\U00e7 bireyleri simetriktir ve konik formludur. Yapraklar\U0131, deri gibi sert, u\U0308\U00e7gen \U015feklinde, u\U00e7lar\U0131 sivri, bat\U0131c\U0131 ve her iki yu\U0308zu\U0308 koyu ye\U015fildir.";
      "turkis_name" = "Maynum \U00c7\U0131kmaz A\U011fac\U0131";
  },
      {
      "bothanical_prop" = "Norfolk adalar\U0131na (Avustralya) \U00f6zgu\U0308 endemik bir tu\U0308rdu\U0308r. Dekoratif ama\U00e7l\U0131 \U00fclkemizde Ege, Akdeniz ve Marmara \U00e7evresinde d\U0131\U00e7 mekan bitkisi olarak kullan\U0131l\U0131r.";
      "latin_name" = "Araucaria heterophylla (Salisb.) Franco";
      "leaf_type" = 1;
      "seed_type" = 1;
      "spreading_area" = "60-70 m\U2019ye kadar boylanabilen bir orman a\U011fac\U0131d\U0131r. Dallar g\U00f6vdeden 4-7\U2019li \U00e7evrel olarak \U00e7\U0131kar. G\U00f6vde kabu\U011fu ince levhalar halinde \U00e7atlakl\U0131d\U0131r. Yapraklar\U0131 2 farkl\U0131 \U015fekildedir: Gen\U00e7 ve yan su\U0308rgu\U0308nlerde a\U00e7\U0131k ye\U015fil, biz gibi uzun, k\U00f6\U015feli ve yumu\U015fak; ya\U015fl\U0131 su\U0308rgu\U0308nlerde ise daha k\U0131sa, daha sert, s\U0131k, birbiri u\U0308zerine binmi\U015f ve u\U00e7 k\U0131s\U0131mlar\U0131 boynuz gibi \U00f6ne do\U011fru k\U0131vr\U0131lm\U0131\U015f olan yapraklar vard\U0131r";
      "turkis_name" = "Salon arokaryas\U0131";
  }
  </code></pre>