使用Combine根据字符串启用按钮

import Combine

class ViewController: UIViewController {
    @IBOutlet weak var textField: UITextField!
    @IBOutlet weak var button: UIButton!
    
    private var cancellables = Set<AnyCancellable>()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        textField.addTarget(self, action: #selector(textFieldDidChange(_:)), for: .editingChanged)
        
        // 使用Combine监听输入框文本变化
        NotificationCenter.default.publisher(for: UITextField.textDidChangeNotification, object: textField)
            .map { ($0.object as? UITextField)?.text ?? "" } // 转换为字符串
            .map { $0.isEmpty } // 判断字符串是否为空
            .assign(to: \.isEnabled, on: button) // 将结果赋值给按钮的isEnabled属性
            .store(in: &cancellables)
    }
    
    @objc func textFieldDidChange(_ textField: UITextField) {
        // 发送文本变化的通知
        NotificationCenter.default.post(name: UITextField.textDidChangeNotification, object: textField)
    }
    
    deinit {
        // 取消Combine订阅
        cancellables.forEach { $0.cancel() }
    }
}