title: UICollectionview slow data reloading
body: <p>I make a request, get data, split them into 10 arrays and it takes like 2 seconds. But sorting them into <code>UICollectionView</code> takes almost 10 seconds to show data. Here is my code:</p>
  
  <pre><code>func makeRequest() {
      let url = URL(string: "https://api.example.com/v1/ticker/?start=" + "\(startingPoint)")
      let task = URLSession.shared.dataTask(with: url!) { (data, response, error) in
          if error != nil {
              print(error!)
          } else {
              if let urlContent = data {
                  do {
                      let jsonResult = try JSONSerialization.jsonObject(with: urlContent, options: JSONSerialization.ReadingOptions.mutableContainers) as! [AnyObject]
                      var i: Int!
                      for i in 0..&lt;jsonResult.count {
                          Global.rankArray.append(String(describing: jsonResult[i]["rank"]!!))
                          // 9 other similar lines 
                      }
                      // Loading some views
                      self.dataCollection.reloadData()
                  } catch {
                      print("Error")
                }
              }
          }
      }
      task.resume()
  }
  </code></pre>
  
  <p>So I can print everything quickly but no data is showing in the <code>UICollectionView</code> until 10 seconds pass. The loading time doesn't rely on the internet connection speed.</p>