多个UITextFields和textDidChangeNotification通知

import UIKit

class ViewController: UIViewController {
    
    let textField = UITextField()
    let label = UILabel()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置 textField 和 label 的布局
        textField.frame = CGRect(x: 20, y: 100, width: 200, height: 30)
        label.frame = CGRect(x: 20, y: 150, width: 200, height: 30)
        
        // 添加到视图
        view.addSubview(textField)
        view.addSubview(label)
        
        // 设置默认文本
        label.text = "Text will appear here"
        
        // 注册通知
        NotificationCenter.default.addObserver(self, selector: #selector(textDidChange(_:)), name: UITextField.textDidChangeNotification, object: textField)
    }
    
    @objc func textDidChange(_ notification: Notification) {
        if let textField = notification.object as? UITextField {
            label.text = textField.text
        }
    }
    
    deinit {
        // 移除通知观察者
        NotificationCenter.default.removeObserver(self, name: UITextField.textDidChangeNotification, object: textField)
    }
}