How do I set custom headers for my web scraping requests in Kanna?

Kanna is a Swift library used for parsing XML and HTML for iOS and macOS applications. It doesn't provide a functionality to make web requests on its own. Instead, it is used in conjunction with networking libraries or native networking APIs like URLSession to download the content, which is then parsed by Kanna.

To set custom headers for web scraping requests in an iOS/macOS application, you would first make the web request using URLSession (or another networking library like Alamofire), and then parse the retrieved data with Kanna.

Here's an example of how to set custom headers using URLSession in Swift and then parse the HTML content with Kanna:

import Foundation
import Kanna

// Your custom headers
let headers = [
    "User-Agent": "YourCustomUserAgent/1.0",
    "Accept-Language": "en-US,en;q=0.5",
    // Add other headers as needed
]

// Create a URL and a URLRequest
if let url = URL(string: "https://example.com") {
    var request = URLRequest(url: url)

    // Set the custom headers
    request.allHTTPHeaderFields = headers

    // Create a URLSessionDataTask to fetch the content
    let task = URLSession.shared.dataTask(with: request) { data, response, error in
        // Check for errors and unwrap the data
        guard let data = data, error == nil else {
            print(error ?? "Unknown error")
            return
        }

        // Parse the HTML content with Kanna
        do {
            let doc = try HTML(html: data, encoding: .utf8)
            // Use Kanna to navigate the parsed HTML...
            for link in doc.xpath("//a | //link") {
                print(link.text ?? "")
            }
        } catch {
            print("Failed to parse HTML: \(error)")
        }
    }

    // Start the task
    task.resume()
}

This example performs the following steps:

1. Defines a dictionary with your custom headers.
2. Creates a URL and URLRequest with the desired URL.
3. Sets the custom headers on the URLRequest.
4. Creates a URLSessionDataTask to send the request and handle the response.
5. Checks for any errors and unwraps the retrieved data.
6. Uses Kanna to parse the HTML content and print the text of all links.

Remember to handle the network requests asynchronously and update the UI on the main thread if you are working with a UI application.

Please note that web scraping can be against the terms of service of some websites. Always ensure that you have permission to scrape a website and that your actions comply with their terms of service and any relevant laws. Additionally, be respectful to the websites you scrape by not overloading their servers with a high number of requests.