IOKit

Apple's C++ framework for developing high-performance hardware drivers and managing device lifecycles on macOS and iOS.

IOKit provides the fundamental object-oriented architecture for hardware interaction across Apple platforms. Built on a subset of C++ (Embedded C++), it eliminates overhead like exceptions and RTTI to ensure kernel stability. The framework manages the I/O Registry: a live database tracking every connected component from Thunderbolt controllers to HID peripherals. Developers use its specialized classes (like IOService and IOWorkLoop) to handle power management, threading, and memory mapping without manual low-level plumbing. It is the bridge between Mach microkernel primitives and the user-space hardware abstraction layer.

https://developer.apple.com/library/archive/documentation/DeviceDrivers/Conceptual/IOKitFundamentals/Introduction/Introduction.html