Question 1

How to install Kanna on Ubuntu for a Swift server project?

Accepted Answer

First, install libxml2-dev using apt-get, then add Kanna to your Package.swift file. Run swift build, and if errors occur, install pkg-config as noted in the README to resolve dependency issues.

Question 2

Kanna vs SwiftSoup: which is better for HTML parsing in Swift?

Accepted Answer

Kanna offers XPath support and cross-platform Linux compatibility, while SwiftSoup is pure Swift but may lack XPath. Choose Kanna if you need XPath queries or Linux deployment; SwiftSoup for simpler iOS/macOS setups without external dependencies.

Question 3

Can Kanna handle XML files with multiple namespaces?

Accepted Answer

Yes, Kanna supports namespaces via the namespaces parameter in xpath queries. Provide a dictionary mapping prefixes to URIs, as shown in the synopsis example, to accurately select elements in namespaced documents.

Question 4

Is Kanna thread-safe for concurrent parsing in Swift apps?

Accepted Answer

The README doesn't specify thread safety, and since it wraps libxml2 which may not be inherently thread-safe, it's advisable to use synchronization mechanisms like locks or queues when parsing documents concurrently to avoid crashes.

Question 5

What are common build errors with Kanna and Swift Package Manager?

Accepted Answer

Missing libxml2 headers often cause build failures. Ensure libxml2 is installed and linked correctly; on macOS, use brew link --force, and on Linux, verify pkg-config is installed to resolve include path issues.

Question 6

How to extract all links from a webpage using Kanna CSS selectors?

Accepted Answer

Parse the HTML with Kanna, then use doc.css("a") to iterate over anchor elements. Access the href attribute via link["href"] and text via link.text, similar to the synopsis example for CSS queries.

Kanna

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