使用情节提要和自定义UITabBarController显示警报

import UIKit

class MyViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置一个按钮来触发警报
        let button = UIButton(type: .system)
        button.setTitle("Show Alert", for: .normal)
        button.addTarget(self, action: #selector(showAlert), for: .touchUpInside)
        view.addSubview(button)
        
        // 布局按钮
        button.translatesAutoresizingMaskIntoConstraints = false
        NSLayoutConstraint.activate([
            button.centerXAnchor.constraint(equalTo: view.centerXAnchor),
            button.centerYAnchor.constraint(equalTo: view.centerYAnchor)
        ])
    }
    
    @objc func showAlert() {
        let alertController = UIAlertController(title: "Alert Title", message: "Alert Message", preferredStyle: .alert)
        let okAction = UIAlertAction(title: "OK", style: .default, handler: nil)
        alertController.addAction(okAction)
        self.present(alertController, animated: true, completion: nil)
    }
}