What is the best practice for handling redirects when scraping with SwiftSoup?

SwiftSoup is a pure Swift library for working with real-world HTML, inspired by the popular Java library Jsoup. While SwiftSoup itself doesn't handle network operations or HTTP redirects, you would typically use URLSession to fetch the web content in Swift, which handles redirects by default.

However, it's essential to understand that web scraping should always be performed ethically and legally, respecting the terms of service of the website and the robots.txt file, which might restrict the scraping of certain content.

When using URLSession to fetch web content, by default, if a server responds with a redirect, the URLSession task will automatically follow that redirect. However, you might want to handle redirects manually, either to inspect the redirect responses or to modify the behavior of the request when a redirect occurs.

Here's how you can handle redirects manually while using URLSession:

First, you need to create a class that conforms to the URLSessionTaskDelegate protocol, where you can implement the urlSession(_:task:willPerformHTTPRedirection:newRequest:completionHandler:) method:

import Foundation

class SessionDelegate: NSObject, URLSessionTaskDelegate {
    func urlSession(_ session: URLSession, task: URLSessionTask, 
                    willPerformHTTPRedirection response: HTTPURLResponse, 
                    newRequest request: URLRequest, 
                    completionHandler: @escaping (URLRequest?) -> Void) {

        // You can inspect the response and the new request here
        print("Redirected from: \(response.url?.absoluteString ?? "") to: \(request.url?.absoluteString ?? "")")

        // If you want to follow the redirect, pass the new request to the completion handler
        completionHandler(request)

        // If you don't want to follow the redirect, pass nil to the completion handler
        // completionHandler(nil)
    }
}

Next, you can use this delegate when creating your URLSession:

let sessionDelegate = SessionDelegate()
let session = URLSession(configuration: .default, delegate: sessionDelegate, delegateQueue: OperationQueue.main)

let url = URL(string: "http://example.com")!
let task = session.dataTask(with: url) { data, response, error in
    // Handle the response here
    if let data = data, let html = String(data: data, encoding: .utf8) {
        do {
            let doc: Document = try SwiftSoup.parse(html)
            // Use SwiftSoup to parse and manipulate the HTML as needed
        } catch {
            print("Error parsing HTML: \(error)")
        }
    } else if let error = error {
        print("Error fetching data: \(error)")
    }
}
task.resume()

When you run this code, if the URL encounters a redirect, the delegate method willPerformHTTPRedirection will be called, and you can decide whether to follow the redirect or not. If you pass nil to the completion handler, the redirect will not be followed, and the task will call its completion handler with the redirect response, allowing you to handle it however you'd like.

Remember that handling redirects properly ensures that your scraper can reach the intended content, even when websites use redirection to manage their URL structure. Always follow best practices and legal guidelines when scraping to avoid misuse of the data and potential legal issues.