如果我在页面完成之前退出页面，如何取消URLSession.shared.dataTask？

class MyViewController: UIViewController, URLSessionDelegate {
    var dataTask: URLSessionDataTask?
    
    func fetchData() {
        let url = URL(string: "https://example.com/data")!
        let request = URLRequest(url: url)
        
        dataTask = URLSession.shared.dataTask(with: request) { (data, response, error) in
            // 处理数据响应
        }
        
        dataTask?.resume()
    }
    
    func cancelDataTask() {
        dataTask?.cancel()
    }
    
    // URLSessionDelegate方法
    func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
        if let error = error as NSError?, error.code == NSURLErrorCancelled {
            // 任务被取消
        } else {
            // 处理其他错误
        }
    }
}