Swift - UITableView

import UIKit
class ViewController: UIViewController,UITableViewDelegate,UITableViewDataSource{
    
    var ctrlnames:[String]?
    var tableView:UITableView?
  

    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.ctrlnames = ["UILabel","UITextField","UIButton","UISwitch","UISegmentControl","UIImageView","UIProgressView","UISlider","UIAlertView"]
        
        self.tableView = UITableView(frame:self.view.frame, style: .plain)
        self.tableView?.delegate = self
        self.tableView?.dataSource = self
        
        self.tableView?.register(UITableViewCell.self, forCellReuseIdentifier: "cellID")
        self.view.addSubview(self.tableView!)
        
        //创建表头标签
        let frame = CGRect(x: 0, y: 0, width: self.view.bounds.size.width, height: 30)
        let headerLabel = UILabel(frame: frame)
        headerLabel.backgroundColor = UIColor.black
        headerLabel.textColor = UIColor.white
        headerLabel.numberOfLines = 0
        headerLabel.lineBreakMode = .byWordWrapping
        headerLabel.text = "常见的 UIKit 控件"
        headerLabel.font = UIFont.italicSystemFont(ofSize: 20)
        self.tableView?.tableHeaderView = headerLabel
    }
    
    //表格行数
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return self.ctrlnames!.count
    }
    
    //单元显示内容
    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let identyfy:String = "cellID"
        let cell = tableView.dequeueReusableCell(withIdentifier: identyfy, for: indexPath)
        cell.accessoryType = .disclosureIndicator
        cell.textLabel?.text = self.ctrlnames![indexPath.row]
        return cell
    }
    
    func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        self.tableView?.deselectRow(at: indexPath, animated: true)
        
        let itemString = self.ctrlnames![indexPath.row]
        
        let alertController = UIAlertController(title: "提示", message: "你选中了\(itemString)", preferredStyle: .alert)
        
        let okAction = UIAlertAction(title: "确定", style: .default, handler: nil)
        
        alertController.addAction(okAction)
        
        self.present(alertController, animated:true, completion: nil)
        
    }
    //滑动删除必须实现的方法
    func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCellEditingStyle, forRowAt indexPath: IndexPath) {
        let index = indexPath.row
        self.ctrlnames?.remove(at: index)
        self.tableView?.deleteRows(at: [indexPath], with: .bottom)
    }
    
    //滑动删除
    func tableView(_ tableView: UITableView, editingStyleForRowAt indexPath: IndexPath) -> UITableViewCellEditingStyle {
        return .delete
    }
    //修改删除按钮的文字
    func tableView(_ tableView: UITableView, titleForDeleteConfirmationButtonForRowAt indexPath: IndexPath) -> String? {
        return "删除"
    }
    
}