urlsession-code-review

Original：🇺🇸 English

Translated

Reviews URLSession networking code for iOS/macOS. Covers async/await patterns, request building, error handling, caching, and background sessions.

2installs

Sourceexistential-birds/beagle

Added on2026-02-04

NPX Install

npx skill4agent add existential-birds/beagle urlsession-code-review

SKILL.md Content

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URLSession Code Review

Quick Reference

Topic	Reference
Async/Await	async-networking.md
Requests	request-building.md
Errors	error-handling.md
Caching	caching.md

Review Checklist

Response Validation

HTTP status codes validated - URLSession does NOT throw on 404/500
Response cast to HTTPURLResponse before checking status
Both transport errors (URLError) and HTTP errors handled

Memory & Resources

Downloaded files moved/deleted (async API doesn't auto-delete)
Sessions with delegates call
```
finishTasksAndInvalidate()
```
Long-running tasks use
```
[weak self]
```
Stored Task references cancelled when appropriate

Configuration

```
timeoutIntervalForResource
```
set (default is 7 days!)
URLCache sized adequately (default 512KB too small)
Sessions reused for connection pooling

Background Sessions

Unique identifier (especially with app extensions)
File-based uploads (not data-based)
Delegate methods used (not completion handlers)

Security

No hardcoded secrets (use Keychain)
Header values sanitized for CRLF injection
Query params via URLComponents (not string concat)

Output Format

markdown

### Critical
1. [FILE:LINE] Missing HTTP status validation
   - Issue: 404/500 responses not treated as errors
   - Fix: Check `httpResponse.statusCode` is 200-299