IOService
IOService is a core class in Apple’s I/O Kit framework, used to implement device drivers within macOS and iOS. It serves as the base class for most driver objects and represents nodes in the I/O Registry, a dynamic database that models hardware devices, buses, and the software drivers that manage them.
The IOService class provides the fundamental lifecycle and service-management facilities that drivers rely on. Driver authors
In addition to lifecycle and matching, IOService handles properties and communication with other kernel components. Drivers
IOService objects exist as nodes in the I/O Registry hierarchy, where parent-child relationships reflect device topology.