如何在iPhone上HTTP连接失败时弹出警报？

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let alert = UIAlertController(title: "连接失败", message: "HTTP连接失败，请检查网络连接。", preferredStyle: .alert)
        
        alert.addAction(UIAlertAction(title: "确定", style: .default, handler: nil))
        
        self.present(alert, animated: true, completion: nil)
    }
}

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let error = NSError(domain: "HTTP连接失败", code: 0, userInfo: [NSLocalizedDescriptionKey: "请检查网络连接。"])
        
        let alert = UIAlertController(title: "连接失败", message: error.localizedDescription, preferredStyle: .alert)
        
        alert.addAction(UIAlertAction(title: "确定", style: .default, handler: nil))
        
        self.present(alert, animated: true, completion: nil)
    }
}