我用UIKit编程。我有一个UITableView在另一个视图控制器中工作正常，我已经把我在那里使用的代码大部分复制到这个VC中，但我没有得到任何错误，UITableView也没有显示。我检查了调试视图层次结构，它也不存在。我不确定这是否相关，但在启动调试视图层次结构时，调试窗口中会重复显示以下消息：[API] Failed to get renderer info (client=0x82b3d507) [0x5 (os/kern) failure]。我在numberOfRowsInSection中的print语句会触发，但在cellForRowAt中的print语句不会触发。WorkoutTemplate及其子结构是没有逻辑的简单数据结构。我在WorkoutTemplate上有一个静态属性，用于在布局UI时使用虚拟数据。

class CreateWorkoutVC: UIViewController, UITableViewDataSource, UITableViewDelegate {
    var exerciseListing: UITableView!
    
    var workoutTemplate: WorkoutTemplate!
    
    init(workoutTemplate: WorkoutTemplate) {
        super.init(nibName: nil, bundle: nil)
        
        self.workoutTemplate = workoutTemplate

        configure()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .systemBackground
    }
    
    private func configure() {
        let padding: CGFloat = 20

        exerciseListing = UITableView(frame: view.frame)

        view.addSubview(exerciseListing)
        
        exerciseListing.register(UITableViewCell.self, forCellReuseIdentifier: "exercise")
        exerciseListing.rowHeight = 50
        exerciseListing.dataSource = self
        exerciseListing.delegate = self
        exerciseListing.translatesAutoresizingMaskIntoConstraints = false
        
        
        NSLayoutConstraint.activate([
            exerciseListing.topAnchor.constraint(equalTo: view.topAnchor, constant: padding),
            exerciseListing.leadingAnchor.constraint(equalTo: view.leadingAnchor, constant: padding),
            exerciseListing.trailingAnchor.constraint(equalTo: view.trailingAnchor, constant: -padding)
        ])
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        print("In numberOfRowsInSection: \(workoutTemplate.exerciseSets.count)")
        return workoutTemplate.exerciseSets.count
    }
    
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "exercise", for: indexPath)
        
        let cellLabel = getCellLabel(withText: workoutTemplate.exerciseSets[indexPath.row].exercise.exerciseName)
        print(workoutTemplate.exerciseSets[indexPath.row].exercise.exerciseName)
        cell.addSubview(cellLabel)
        
        let padding: CGFloat = 8
        
        NSLayoutConstraint.activate([
            cellLabel.centerYAnchor.constraint(equalTo: cell.centerYAnchor),
            cellLabel.leadingAnchor.constraint(equalTo: cell.leadingAnchor, constant: padding),
            cellLabel.trailingAnchor.constraint(equalTo: cell.trailingAnchor, constant: -padding),
            cellLabel.heightAnchor.constraint(equalTo: cell.heightAnchor)
        ])
        
        cell.backgroundColor = .secondarySystemBackground
        
        return cell
    }
    
    func getCellLabel(withText labelText: String) -> UILabel {
        let cellLabel = UILabel(frame: .zero)
        cellLabel.text = labelText
        cellLabel.textColor = .label
        cellLabel.adjustsFontSizeToFitWidth = true
        cellLabel.minimumScaleFactor = 0.90
        cellLabel.lineBreakMode = .byTruncatingTail
        cellLabel.translatesAutoresizingMaskIntoConstraints = false
        
        cellLabel.textAlignment = .left
        cellLabel.font = UIFont.systemFont(ofSize: 16, weight: .bold)
        
        return cellLabel
    }
}

数据结构：

struct WorkoutTemplate {
    let workoutName: String
    var exerciseSets: [ExerciseSet]
    
    mutating func addExerciseSet(exerciseSet: ExerciseSet) {
        exerciseSets.append(exerciseSet)
    }
    
    static let exampleWorkouts = [WorkoutTemplate(workoutName: "Upper Body 1", exerciseSets: [ExerciseSet(exercise: Exercise(exerciseId: UUID(), exerciseName: "Bench Press"), sets: 3, targetReps: 8, targetRPE: 8, restPeriod: 2), ExerciseSet(exercise: Exercise(exerciseId: UUID(), exerciseName: "T-Bar Row"), sets: 3, targetReps: 8, targetRPE: 8, restPeriod: 3)]), WorkoutTemplate(workoutName: "Lower Body 1", exerciseSets: [ExerciseSet(exercise: Exercise(exerciseId: UUID(), exerciseName: "Hack Squats"), sets: 3, targetReps: 8, targetRPE: 8, restPeriod: 2), ExerciseSet(exercise: Exercise(exerciseId: UUID(), exerciseName: "Leg Ext"), sets: 3, targetReps: 8, targetRPE: 8, restPeriod: 3)])]
}

struct ExerciseSet {
    let exercise: Exercise
    let sets: Int
    let targetReps: Int
    let targetRPE: Int
    let restPeriod: Int
}

struct Exercise {
    let exerciseId: UUID
    let exerciseName: String
}