# Objective C > Objective-C for legacy iOS/macOS development with manual memory. Use for .m files. Use when this capability is needed. - Skill: `tomevault-io/objective-c` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/objective-c` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/objective-c/raw - Safety review: pending (external: skill-scanner PASS, skillspector PASS) - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: AI & ML - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/objective-c --- # Objective-C Objective-C is in **maintenance mode**. New features are rare, but it powers the Apple ecosystem's foundation. It allows mixing C++ (`.mm`) loosely. ## When to Use - **Legacy iOS/macOS**: Maintaining apps created before 2014. - **C++ Interop**: Obj-C++ is often the bridge between C++ engines and Swift. - **Runtime Swizzling**: Dynamic method replacement (used by Analytics SDKs). ## Core Concepts ### Message Passing `[object method:argument]`. Dynamic binding at runtime. ### ARC Automatic Reference Counting. (Retain/Release). ### Headers `.h` (interface) and `.m` (implementation). ## Best Practices (2025) **Do**: - **Use Nullability Annotations**: `nullable`, `nonnull` to aid Swift interop. - **Use Modern Syntax**: `@[@"a", @"b"]` for arrays. - **Migrate to Swift**: New features should be written in Swift. **Don't**: - **Don't use manual retain/release**: Always ensure ARC is on. ## References - [Apple Developer Documentation](https://developer.apple.com/) --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/g1joshi) — claim your Tome and manage your conversions.