title: Can any one help me to solve this error using Swift
body: <p>would you please help me to solve this error .I'am trying to download an Image From Firebase Database, this is my code and I put a snapshot for the error . Thanks<a href="https://i.stack.imgur.com/nemCh.png" rel="nofollow noreferrer">This is a snapshot for the error in Xcode</a></p>
  
  <pre><code>  import UIKit
    import FirebaseDatabase
  
    class ViewController: UIViewController , UITableViewDataSource , UITableViewDelegate {
  
     @IBOutlet weak var tableView: UITableView!
  
     var ref:FIRDatabaseReference?
     var Handle:FIRDatabaseHandle?
     var myClass = [Post]() 
  
     override func viewDidLoad() {
      super.viewDidLoad()
  
      tableView.delegate = self
      tableView.dataSource = self
  
      ref=FIRDatabase.database().reference()
  
      Handle = ref?.child("Posts").observe(.childAdded, with: { (snapshot) in
            let post = snapshot.valueInExportFormat()
  
            for url in post! as! [Post] {        // Error Here
               self.myClass.append(url)
              self.tableView.reloadData()
            }
  
            override func didReceiveMemoryWarning() {
            super.didReceiveMemoryWarning()
            // Dispose of any resources that can be recreated.
      }
  
     public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -&gt; Int{
            return myClass.count
       }
  
     public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -&gt; UITableViewCell {
  
          if  let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)as? TableViewCell{
  
         cell.MyImage.alpha = 0
         cell.textLabel?.text = PostData[indexPath.row]
  
         DispatchQueue.main.async(execute: {
  
         let imgurl = URL(string : self.myClass [(indexPath as       NSIndexPath).row].url)
         let imgdata = NSData(contentsOf: imgurl!)
         cell.MyImage.image = UIImage(data: imgdata as! Data)
  
         UIView.animate(withDuration: 0.5, animations: {
              cell.MyImage.alpha = 1
         })
     })
  
      return cell
  
      } else {
  
          let cell = TableViewCell()
          DispatchQueue.main.async(execute: {
  
              let imgurl = URL(string : self.myClass [(indexPath as NSIndexPath).row].url)
              let imgdata = NSData(contentsOf: imgurl!)
              cell.MyImage.image = UIImage(data: imgdata as! Data)
          })
          return cell
      }
  
   }
  
  
  
  
  
       }
  
  
      })
  
  
  }
  </code></pre>