1

class ViewController: UIViewController, UITableViewDataSource {
    var myView: UIView!

    override func viewDidLoad() {
    super.viewDidLoad()

    var myView = UIView(frame: CGRectMake((width-50)/2, (height-50)/2, 50, 50))
    myView.backgroundColor = UIColor(red: 16/255.0, green: 57/255.0, blue: 100/255.0, alpha: 0.9)
    myView.layer.cornerRadius = 16

    self.view.addSubview(myView)
    myView.alpha = 0
    }

    func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
        self.myView.alpha = 1 // <-- Error: fatal error: unexpectedly found nil while unwrapping an Optional value
    }