Web Scraping with Objective-C & ChatGPT

Sep 25, 2023 ยท 3 min read

Objective-C is a powerful language for web scraping on Apple platforms like iOS and macOS. ChatGPT is an AI assistant that can provide explanations and generate code for scraping tasks. This article covers web scraping in Objective-C with ChatGPT's help.

Setting Up Objective-C for Web Scraping

You'll need Xcode installed, along with these frameworks/libraries:

// Foundation for HTTP requests
#import <Foundation/Foundation.h>

// libxml2 for HTML parsing
#import <libxml/HTMLparser.h>

// CSVParser for CSV parsing
#import "CSVParser.h"

Introduction to Web Scraping in Objective-C

Web scraping involves sending requests to websites and extracting data from the HTML, JSON or XML responses. Useful Objective-C options:

  • NSURLSession - Making HTTP requests
  • libxml2 - HTML/XML parsing
  • XPathQuery - XPath queries for DOM traversal
  • Typical web scraping workflow:

  • Send HTTP request to download a page
  • Parse response and extract relevant data
  • Store scraped data
  • Repeat for other pages
  • Using ChatGPT for Web Scraping Help

    ChatGPT is an AI assistant created by Anthropic to be helpful, harmless, and honest. It can provide explanations and generate code snippets for web scraping:

    Getting Explanations

    Ask ChatGPT to explain web scraping concepts or specifics:

  • How to use libxml2 to extract text from paragraph elements
  • Strategies for scraping content spread across pagination
  • Generating Code Snippets

    Give a description of what you want to scrape and have ChatGPT provide starter Objective-C code:

  • Scrape product listings into a CSV file
  • Parse date strings into NSDate when extracting
  • Validate any code before using.

    Improving Prompts

    Ask ChatGPT to suggest ways to improve your prompt if it doesn't provide helpful responses.

    Asking Follow-up Questions

    Chat with ChatGPT to get explanations for any other questions you have.

    Explaining Errors

    Share any errors and ask ChatGPT to debug and explain the problem.

    Web Scraping Example Using ChatGPT

    Let's walk through scraping a Wikipedia page with ChatGPT's assistance.

    Goal

    Extract the chronology table from: https://en.wikipedia.org/wiki/Chronology_of_the_universe

    Step 1: Download page

    ChatGPT: Objective-C code to download this page:
    <https://en.wikipedia.org/wiki/Chronology_of_the_universe>
    
    // ChatGPT provides this code
    NSURL *url = [NSURL URLWithString:@"<https://en.wikipedia.org/wiki/Chronology_of_the_universe>"];
    NSURLSessionDataTask *task = [[NSURLSession sharedSession] dataTaskWithURL:url completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
      // Handle response
    }];
    [task resume];
    

    Step 2: Inspect HTML, table has class wikitable

    Step 3: Extract table data to CSV

    ChatGPT: Objective-C code to extract wikitable table to CSV
    
    // ChatGPT provides this code
    htmlDocPtr doc = htmlReadMemory(html.UTF8String, html.length, "", NULL, HTML_PARSE_NOBLANKS | HTML_PARSE_NOERROR | HTML_PARSE_NOWARNING | HTML_PARSE_NONET);
    
    xmlNodePtr table = xpath_node(doc, "//table[contains(@class, 'wikitable')]");
    
    // Extract headers
    NSArray *headers = //...
    
    // Extract rows
    NSArray *rows = //...
    
    // Write to CSV
    //...
    
    xmlFreeDoc(doc);
    

    This shows using ChatGPT to get Objective-C scraping code quickly.

    Conclusion

    Key points:

  • Objective-C provides native iOS/macOS scraping
  • ChatGPT can explain concepts and provide Objective-C code
  • Inspect HTML to understand how to extract data
  • Follow best practices like throttling requests, randomizing user agents
  • Web scraping allows gathering data from websites at scale
  • ChatGPT + Objective-C is great for Apple scraping apps.

    However, some limitations:

  • Handling anti-scraping measures like CAPTCHAs
  • Avoiding IP blocks when running locally
  • Rendering complex JavaScript pages
  • A more robust solution is using a web scraping API like Proxies API

    Proxies API provides:

  • Millions of proxy IPs to prevent blocks
  • Automated solving of CAPTCHAs
  • JavaScript rendering with headless browsing
  • Simple API instead of running your own scrapers
  • Easily scrape any site:

    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"<https://api.proxiesapi.com/?url=example.com&key=XXX>"]];
    
    // Send request
    

    Get started now with 1000 free API calls to supercharge your web scraping!

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