以编程方式创建的UITextField不加载文本IOS swift

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建UITextField对象
        let textField = UITextField()
        
        // 设置UITextField的属性
        textField.frame = CGRect(x: 50, y: 50, width: 200, height: 30)
        textField.borderStyle = .roundedRect
        textField.backgroundColor = .white
        
        // 设置代理
        textField.delegate = self
        
        // 添加UITextField到视图
        view.addSubview(textField)
    }
    
    // UITextFieldDelegate方法示例
    func textFieldDidChangeSelection(_ textField: UITextField) {
        print("文本框内容变化：\(textField.text ?? "")")
    }
}