Tableview Does Not Show Data

Swift TableView in a UIView not displaying data

try this:

override func viewDidLoad() {
    super.viewDidLoad()

    // Add this
    tableView.delegate = self
    tableView.dataSource = self
}

tableView not showing data values

You will need to call the following methods before it listens to cellForRowAt:

override func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return 1
    }

another common problem is that the frame of the table is not set (e.g. inside a UITableViewCell, with automatic dimensions). The table requires a frame before it gets cells.

TableView does not show data

Swift solution:

tableView.reloadData()

If you are calling it not from the main thread:

DispatchQueue.main.async {
    self.tableView.reloadData()
}

How to fix Table View Cells not showing on launch?

Try debugging first that if the table view delegate and data source methods are called or not. Then reloading the table view after the API response is stored in the array. After this, self.items.append(show).

Try this.

 switch response.result {
            case .success(let shows):
                print("Succes: \(shows)")
                shows.forEach { show in
                    self.items.append(show)
                }
                self.tableView.reloadData()
            case .failure(let error):
                print("Eror: \(error)")
            }

Javafx TableView not showing data

You need to actually tell the TableView HOW to display the data. This is done using a CellValueFactory. Basically, you need to tell each column of the table what type of data it holds and where it gets that data from.

You need to start by defining your columns (give them an fx:id either in the FXML file or in SceneBuilder):

@FXML
TableColumn<Parameter, String> colCategory;
@FXML
TableColumn<Parameter, String> colSubCategory;
@FXML
TableColumn<Parameter, String> colSubSubCategory;

Each TableColumn takes two Type parameters. The first defines the object being displayed (Parameter). The second is the data type for this column (all yours are String).

Once the columns are defined, you need to set their CellValueFactory in your initialize() method:

colCategory.setCellValueFactory(new PropertyValueFactory<Parameter, String>("cat"));
colSubCategory.setCellValueFactory(new PropertyValueFactory<Parameter, String>("subCat"));
colSubSubCategory.setCellValueFactory(new PropertyValueFactory<Parameter, String>("subSubCat"));

Here you are telling each column where to find the data to be displayed. The last argument on the line, in the quotes, is the name of your property within the Parameter object.

So, when JavaFX populates your table, it will takes these steps to populate each column (colCategory, for example):

1. Get the CellValueFactory for colCategory.
2. The factory is a PropertyValueFactory, so determine which class holds the property (in this case it is the Parameter class)
3. Look in the Parameter class for a String property by the name of "cat"
4. Populate the column's cell with the value of the cat property.

iOS UITableView Not Showing

Try to refactor you code using a completion handler without using the delegation pattern.

in your network file:

enum ApiError: Error {
    case network(Error)
    case genericError
    case httpResponseError
    case invalidData
    case decoding
    // you can handle your specific case 
}


  func network(completion: @escaping ( _ error: ApiError?, _ users: [GitHub]?)-> Void) {
        let url = "https://api.github.com/users"
        let request: URLRequest?
        
        if let URL = URL(string: url) {
            request = URLRequest(url: URL)
            URLSession.shared.dataTask(with: request!) { result, response, error in
                if let error = error {
                    completion(.network(error), nil)
                    return
                }
                guard let httpResponse = response as? HTTPURLResponse,
                      (200...299).contains(httpResponse.statusCode) else {
                          completion( .httpResponseError, nil)
                          return
                      }
                guard let data = result else {
                    completion(.invalidData, nil)
                    return
                }
                do {
                    let decodedData = try JSONDecoder().decode([GitHub].self, from: data)
                    completion(nil, decodedData)
                } catch {
                    completion(.decoding, nil)
                }
            }
            .resume()
        }
    }

then inside your ViewController you can use it this way:

   override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        network.network { [weak self] error, users in
            guard let self = self else { return }
            if let error = error {
                print(error)
                return
            }
            DispatchQueue.main.async {
                guard let users = users else { return }
                self.users = users
                self.tableView.reloadData()
            }
        }
    }

if it still doesn't show and cellForRow doesn't get called, you probably have a problem with your constraints and the tableView frame is zero (either height, width or both).

Try to debug setting a breakpoint inside numberOfRowsInSection and then in your debug area po tableView or just print the tableView and check if width or height is zero. it will be probably get called a few times. The first time the frame should be zero but at some point you should get a frame with height and width. If don't then check your constraints.

You can check my example which has a table view 375 x 641

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