objc2 is a Rust library that provides safe, idiomatic bindings to Apple's Objective-C runtime and a vast portion of its system frameworks (Foundation, AppKit, Metal, CoreFoundation, and hundreds more). The core crate wraps the Objective-C runtime with type-safe message sending, class definition, reference counting via Retained<T>, and protocol support. Around it, the workspace includes supporting crates for Objective-C blocks (block2), Grand Central Dispatch (dispatch2), a header translator that auto-generates Rust code from Apple's SDK headers, and a documentation parser (apple-doc). The architecture is a large Rust workspace (hundreds of crates) with a clear separation: a lightweight runtime layer (objc2-encode, objc2-exception-helper, objc2-proc-macros), the main objc2 crate with macros and runtime types, and generated framework crates that follow a uniform pattern (extern_class!, extern_methods!, etc.). The project places heavy emphasis on safety and correctness, employing compile-time encoding verification, fuzz testing, assembly-level baseline tests for optimized message sending, and UI tests to catch type errors at compile time. Despite its complexity, the code exhibits strong craftsmanship: the macro infrastructure is well-organized, memory management is carefully designed (two-phase initialization, drop flags, Writeback helpers), and performance-critical paths use inline assembly for retain/autorelease optimization. The project is actively maintained with a modern toolchain, CI against multiple runtimes (Apple, GNUstep, ObjFW), and thorough documentation. It stands as the most comprehensive Rust-to-Objective-C bridge available, suitable for building native macOS/iOS applications entirely in Rust.
SwiftyFitsize is an iOS SDK that provides screen size adaptation for UI elements. It allows developers to define UI dimensions based on a reference design size and automatically scales those dimensions to fit different screen sizes, with special handling for iPhone vs iPad differences and safe area considerations (notch, home indicator). The library offers both operator-based syntax (~ value) and function-based syntax for flexibility, plus Interface Builder support through UIKit extensions. It includes a property wrapper for reusable adapted values and maintains full Objective-C compatibility through a bridging header.