axiom▌

Low-level synchronization primitives for when actors are too slow or heavyweight.

Systematic diagnosis and resolution of app hangs. A hang occurs when the main thread is blocked for more than 1 second, making the app unresponsive to user input.

Systematic Xcode build performance analysis and optimization. Core principle: Measure before optimizing, then optimize the critical path first.

Porting OpenGL/OpenGL ES or DirectX code to Metal on Apple platforms.

Core Data issues manifest as production crashes from schema mismatches, mysterious concurrency errors, performance degradation under load, and data corruption from unsafe migrations. Core principle 85% of Core Data problems stem from misunderstanding thread-confinement, schema migration requirements, and relationship query patterns—not Core Data defects.

Core principle 90% of file storage problems stem from choosing the wrong storage location, misunderstanding file protection levels, or missing backup exclusions—not iOS file system bugs.

Purpose: Comprehensive reference for file-based iCloud sync using ubiquitous containers Availability: iOS 5.0+ (basic), iOS 8.0+ (iCloud Drive), iOS 11.0+ (modern APIs) Context: File-based cloud storage, not database (use CloudKit for structured data)

Apple bundles for-LLM markdown documentation inside Xcode. These are authoritative, up-to-date guides and diagnostics written by Apple engineers. Use them alongside Axiom skills for the most accurate information.

Core principle: Core Data is a mature object graph and persistence framework. Use it when needing features SwiftData doesn't support, or when targeting older iOS versions.

Comprehensive API reference for modern Core Location (iOS 17+).