error message "Unexpectedly found nil while unwrapping an Optional value" even its cell is not nil

xcode: 9.4.1

I'm creating a simple table view but I keep getting the same "Unexpectedly found nil while unwrapping an Optional value" error when it comes to set a value to a component in each cell.

import UIKit class ViewController: UIViewController,UITableViewDelegate,UITableViewDataSource { @IBOutlet weak var conditionTable: UITableView! var conditions = [Condition]() override func viewDidLoad() { super.viewDidLoad() conditionTable.register(ConditionCell.self, forCellReuseIdentifier: "conditionCell") conditionTable.delegate = self conditionTable.dataSource = self setInitData() } override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() // Dispose of any resources that can be recreated. } func setInitData() { conditions.append(Condition(name: "a")) conditions.append(Condition(name: "b")) } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return conditions.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { guard let cell: ConditionCell = tableView.dequeueReusableCell(withIdentifier: "conditionCell") as? ConditionCell else { fatalError() } print(cell.conditionLabel.text) // cell.setCell(condition: conditions[indexPath.row]) return cell } } 

I did name my custom cell "ConditionCell" and I did name the identified "conditionCell".

Here is my custom cell class. I did add the component(label) reference to the class. It looks like the custom view class is successfully loaded (not nil) however its component (label) is not.

import UIKit class ConditionCell: UITableViewCell { @IBOutlet weak var conditionLabel: UILabel! func setCell(condition: Condition) { print(conditionLabel) conditionLabel.text = condition.name } }