Say I create a tableView in navigation controller programmatically. After removing storyboard file and its reference. I put all UI initialization and constraints code into `loadView()` as below code.

Running with real device, but the table view is not showed up, and soon this waring pops up.

If I put those code in `viewDidLoad`, everything works fine. So, how could I track down this issue? I have searched some similar threads but without fixing my problem.

> 
> warning: could not execute support code to read Objective-C class data
> in the process. This may reduce the quality of type information
> available.
> 
> 
> 

```
class ViewController: UIViewController, UITableViewDelegate, UITableViewDataSource, UIImagePickerControllerDelegate, UINavigationControllerDelegate {
    let table = UITableView()
    var pictures = [Picture]()
    let defaults = UserDefaults.standard

    override func viewDidLoad() {
        super.viewDidLoad()

        // if put code in loadView() into here, everything works fine.
        loadData()
    }

    override func loadView() {
        title = "My Pictures"
        navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(addPicture))

        view.addSubview(table)
        table.delegate = self
        table.dataSource = self
        table.register(PictureCell.self, forCellReuseIdentifier: "picture")
        table.translatesAutoresizingMaskIntoConstraints = false
        table.rowHeight = 120

        NSLayoutConstraint.activate([
            table.topAnchor.constraint(equalTo: view.topAnchor),
            table.leadingAnchor.constraint(equalTo: view.leadingAnchor),
            table.trailingAnchor.constraint(equalTo: view.trailingAnchor),
            table.bottomAnchor.constraint(equalTo: view.bottomAnchor),
        ])
    }

    func loadData() {
        DispatchQueue.global().async { [weak self] in
            if let savedPcitures = self?.defaults.object(forKey: "pictures") as? Data {
                let jsonDecoder = JSONDecoder()
                do {
                    self?.pictures = try jsonDecoder.decode([Picture].self, from: savedPcitures)
                } catch {
                    print("Failed to load pictures.")
                }
            }
            DispatchQueue.main.async {
                self?.table.reloadData()
            }
        }
    }

    @objc func addPicture() {
        let picker = UIImagePickerController()
        if UIImagePickerController.isSourceTypeAvailable(.camera) {
            picker.sourceType = .camera
        } else {
            fatalError("Camera is not available, please use real device")
        }
        picker.allowsEditing = true
        picker.delegate = self
        present(picker, animated: true)
    }

...

```

[![enter image description here](https://i.stack.imgur.com/Wg273.png)](https://i.stack.imgur.com/Wg273.png)