macOS 15 Sequoia - Developer Cheat Sheet

Core Platform Changes

Xcode 16 & Swift 6

• Swift 6: New concurrency safety modes
• Predictive Code Completion: On-device ML for Swift/Apple SDKs
• Explicit Module Builds: Default for C/Objective-C, opt-in for Swift. Better parallelism, faster debugging
• DWARF5: Default debug format for macOS Sequoia + iOS 18 targets, smaller dSYM bundles
• Thread Performance Checker: Detects disk writes, slow launches
• Build Timeline: Shows explicit module phases

Apple Intelligence APIs

Privacy Architecture: On-device processing for most tasks, Private Cloud Compute for complex requests (servers use Apple silicon, data never stored/accessible to Apple, code independently inspectable)

Writing Tools API: Automatic in standard text views, custom integration available Image Playground API: In-app image generation Genmoji: Image-based personalized emoji Enhanced Siri + App Intents: Hundreds of new actions, cross-app orchestration

• Use Transferable API, File Representations, Item Providers
• New error handling, deferred properties, associated enums

Core ML Updates:

• Optimized generative AI models on-device
• Core ML Tools: Granular/composable weight compression for LLMs and diffusion models
• Multi-function models with state management for flexible LLM/adapter execution
• New MLTensor type for multi-dimensional arrays
• Enhanced performance reports with operation cost insights