Kanna (also known as SwiftSoup or SwiftSoup for Swift language) is a parsing library for HTML and XML. It does not have the built-in capabilities to handle web scraping directly, such as making HTTP requests or handling sessions. However, you can use it in conjunction with other libraries or methods to scrape content from websites.
When scraping websites, getting blocked or banned is a common issue. Here are some best practices to avoid getting blocked or banned while scraping with Kanna or any other scraping tool:
1. Respect robots.txt
Before scraping a website, check the robots.txt file to see if the website owner has disallowed scraping for certain parts of the site. You should respect these rules to avoid being blocked.
2. Use Headers
Set a User-Agent and other headers to make your requests look more like they are coming from a real browser.
let url = URL(string: "https://example.com")!
var request = URLRequest(url: url)
request.setValue("Mozilla/5.0 (compatible; MyBot/1.0; +http://www.mywebsite.com/bot.html)", forHTTPHeaderField: "User-Agent")
// Add other headers as needed
3. Limit Request Rate
Do not send too many requests in a short period of time. Implement delays between requests to mimic human browsing behavior.
import Foundation
func scrapeWithDelay() {
for url in urlsToScrape {
let data = try? Data(contentsOf: url)
// Perform your scraping logic here
// Wait for a few seconds before making the next request
sleep(2) // Sleeps for 2 seconds. Use a random delay to be more human-like.
}
}
4. Use Proxies
To prevent your IP address from being banned, use proxies to distribute your requests over multiple IP addresses.
// This is a conceptual example and does not directly apply to Swift/Kanna
// You would need to implement proxy handling in your HTTP request logic
request.setValue("http://your-proxy-address:port", forHTTPHeaderField: "Proxy")
5. Rotate User-Agents
Randomly change the User-Agent and possibly other headers to make each request appear as if it is coming from a different browser.
6. Handle Errors Gracefully
If you encounter a 403 (Forbidden) or 429 (Too Many Requests) HTTP status code, handle it by pausing the scraper for a while or switching IPs/proxies.
7. Use Sessions and Cookies
Some sites require a session to be maintained. Use cookies and session information to mimic a logged-in user.
8. Avoid Scraping JavaScript-Heavy Sites with Kanna Alone
Kanna does not execute JavaScript. For sites that heavily rely on JavaScript to render content, consider using a headless browser such as Puppeteer or Selenium.
9. Be Ethical and Legal
Always ensure that your scraping activities are in compliance with the website's terms of service and legal regulations such as the GDPR or the CCPA.
10. Contact the Website
If you need large amounts of data from a website, consider reaching out to the website owner to request access to the data, possibly through an API or a data dump.
Remember, web scraping can be a legally grey area, and it's essential to respect the website, its resources, and its terms of service. If a website makes it hard to scrape, it's possible they do not want their data to be scraped, and you should consider this before proceeding.
