logging-setup

Replace print() statements with Apple's structured logging system (os.log/Logger) for better debugging, privacy controls, and Console.app integration.

When This Skill Activates

Use this skill when the user:

• Asks to "add logging" or "set up logging"
• Wants to "replace print statements"
• Mentions "os.log", "Logger", or "structured logging"
• Asks about "debug logging" or "production logging"
• Wants to audit print() usage in their codebase

Why Logger Over print()

| print() | Logger | |---------|--------| | Always executes | Debug logs compiled out in Release | | No filtering | Filter by subsystem/category in Console.app | | No privacy | .private, .public, .sensitive annotations | | String interpolation always runs | Deferred evaluation (performance) | | Not in Console.app | Full system integration |

Pre-Generation Checks

1. Project Context Detection

• [ ] Check deployment target (Logger requires iOS 14+ / macOS 11+)
• [ ] Search for existing Logger/os.log usage
• [ ] Identify source file locations (Sources/, App/, etc.)

2. Conflict Detection

Search for existing logging:

Glob: **/*Logger*.swift
Grep: "import OSLog" or "os_log"

If found, ask user:

• Extend existing logging?
• Replace with new implementation?
• Create separate logger?

Modes of Operation

Mode 1: Audit

Find all print() statements and report:

Grep: print\s*\(

Report format:

• File:line - print statement
• Severity: Info/Warning/Error (based on context)
• Suggested Logger level

Mode 2: Generate

Create logging infrastructure from scratch.

Mode 3: Migrate

Convert existing print() to Logger with suggestions.

Configuration Questions

Ask user via AskUserQuestion:

1. Categories needed?

   • Network, Auth, UI, Data (defaults)
   • Custom categories?

2. Include migration helpers?

   • Extension on String for quick migration
   • Temporary print-to-log bridge

Generation Process

Step 1: Create AppLogger.swift

Read template from templates/AppLogger.swift and customize:

• Set subsystem from Bundle.main.bundleIdentifier
• Add user-specified categories
• Include usage examples in comments

Step 2: Determine File Location

Check project structure:

• If Sources/ exists → Sources/Logging/AppLogger.swift
• If App/ exists → App/Logging/AppLogger.swift
• Otherwise → Logging/AppLogger.swift

Step 3: Provide Migration Guidance

Show examples of converting common print patterns:

// Before
print("User logged in: \(email)")

// After
AppLogger.auth.info("User logged in: \(email, privacy: .private)")

Output Format

After generation, provide:

Files Created

• [Path]/Logging/AppLogger.swift

Integration Steps

1. Import in files: import OSLog (not needed if using AppLogger)
2. Replace print() calls with AppLogger.[category].level
3. Add privacy annotations for sensitive data

Privacy Annotations Guide

• .public - Safe to log (IDs, counts, non-sensitive)
• .private - Redacted in release (emails, names)
• .sensitive - Always redacted (passwords, tokens)

Console.app Usage

1. Open Console.app
2. Filter by subsystem: com.yourapp
3. Filter by category: Network, Auth, etc.

Testing Instructions

1. Add a test log: AppLogger.general.debug("Test log")
2. Run app, check Xcode console
3. Open Console.app, filter by your app's subsystem

References

• logger-patterns.md - Best practices and privacy levels
• migration-guide.md - Converting print() to Logger
• templates/AppLogger.swift - Template file