Parsing in Swift: Create a Data Parser in 30 Minutes

Why Swift is the Ideal Language for Parsing That Nobody Talks About

When it comes to collecting data from the internet, everyone immediately thinks of Python with its BeautifulSoup and Scrapy. But what if I told you that Swift, the language you use for iOS apps, is capable of no less? Yes, you heard that right. Parsing in Swift is not just a novelty, but a powerful tool that can run 2-3 times faster than Python on the same tasks. And today we will prove it.

In this article, you will learn how to set up the environment, write your first parser in Swift, handle errors, and save data. We won't use complex abstractions — only clean, understandable code that you can run in just 15 minutes.

What is Parsing and Scraping in Swift?

Swift parsing is the process of extracting structured data from web pages or documents using the Swift programming language. Unlike classic web scraping in Python, Swift offers native integration with iOS/macOS, making it ideal for creating applications that collect data themselves.

Main use cases for Swift data scraping:

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• Collecting prices from online stores for competitor monitoring
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• Extracting contact data from directory websites
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• Analyzing news feeds and blogs
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• Creating custom APIs for applications (when no official API exists)
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For parsing in Swift, we will use two key technologies: URLSession for downloading HTML pages and the SwiftSoup library for parsing the HTML document. SwiftSoup is an analog of Python's BeautifulSoup, but written in pure Swift.

Project Installation and Setup

To start, we need to install SwiftSoup. The easiest way is through Swift Package Manager. Create a new project or open an existing one in Xcode, then add the dependency:

// In Package.swift\ndependencies: [\n    .package(url: "https://github.com/scinfu/SwiftSoup.git", from: "2.6.0")\n]

Or, if you are working with SPM without Xcode, simply add the line above to your Package.swift.

An alternative method is to use CocoaPods:

pod 'SwiftSoup', '~> 2.6.0'

After installation, import the library into your code:

import SwiftSoup\nimport Foundation

Done! Now we can start writing the parser.

Writing Your First Parser in Swift: Step by Step

Let's write a parser that extracts article titles from the Hacker News homepage (news.ycombinator.com). This is a classic task for learning parsing.

Step 1: Loading the HTML Page

Use URLSession for asynchronous data loading. Swift is a language with strong support for async/await, so we will use the modern approach.

func fetchHTML(from urlString: String) async throws -> String {\n    guard let url = URL(string: urlString) else {\n        throw URLError(.badURL)\n    }\n    \n    let (data, _) = try await URLSession.shared.data(from: url)\n    guard let html = String(data: data, encoding: .utf8) else {\n        throw URLError(.cannotDecodeContentData)\n    }\n    \n    return html\n}

Note: we return an HTML string. This is the raw data that we will parse.

Step 2: Parsing HTML with SwiftSoup

Now for the interesting part — data extraction. SwiftSoup works like CSS selectors: you specify which elements you want to retrieve.

func parseTitles(from html: String) throws -> [String] {\n    let doc = try SwiftSoup.parse(html)\n    let titles = try doc.select(".titleline a").array()\n    \n    var result: [String] = []\n    for title in titles {\n        let text = try title.text()\n