Kanna is a Swift library for parsing XML and HTML, commonly used with iOS and macOS applications. Kanna provides the ability to navigate and search the DOM of an HTML document, making it useful for extracting data from web pages. However, directly scraping multimedia content such as images and videos is not within the scope of Kanna itself. Instead, Kanna can be used to identify the URLs or paths to these multimedia resources within the HTML document, which can then be downloaded using other means.
Here's a basic example of how you might use Kanna to find the URLs of images on a web page and then download them using Swift's URLSession. Please note that scraping content is subject to the terms of service of the website you are scraping from, and you should always seek permission before downloading content.
import Kanna
func scrapeImageURLs(fromHTML html: String) -> [URL] {
var imageURLs = [URL]()
// Parse the HTML content using Kanna
if let doc = try? HTML(html: html, encoding: .utf8) {
// Search for image tags and extract the src attribute
for image in doc.xpath("//img[@src]") {
if let src = image["src"], let imageURL = URL(string: src) {
imageURLs.append(imageURL)
}
}
}
return imageURLs
}
func downloadImage(fromURL url: URL) {
let task = URLSession.shared.dataTask(with: url) { data, response, error in
guard let data = data, error == nil else {
print(error ?? "Unknown error")
return
}
// Handle the downloaded image data, e.g., save to disk
// ...
}
task.resume()
}
// Example usage
let htmlContent = "<html>...</html>" // Replace with actual HTML content
let imageURLs = scrapeImageURLs(fromHTML: htmlContent)
for imageURL in imageURLs {
downloadImage(fromURL: imageURL)
}
In the example above, scrapeImageURLs is a function that takes an HTML string, parses it using Kanna, and extracts the src attributes of <img> tags to create an array of URL objects. downloadImage is a function that takes a URL, uses URLSession to download the image data, and handles it appropriately (e.g., saving it to disk).
For videos, the approach would be similar; you would search for <video> tags or perhaps <source> tags within them, extract the relevant attributes that contain the video URLs, and then download these using Swift's networking APIs or other appropriate libraries.
Remember that web scraping can be a legally and ethically complex activity. Always respect the website's robots.txt file and terms of service. If a website provides an API, it is preferable to use that API for accessing data, as it is more reliable and respectful of the website's infrastructure and intellectual property.
