Perfect for intermediate and expert developers wanting to take a deeper dive into advanced topics, CFHipsterRef: Low-Level Programming on iOS & Mac OS X covers the core technologies powering Cocoa, Objective-C, and the operating system itself, including:

Kernel

Objective-C Runtime

Clang

OSAtomic

Grand Central Dispatch

Inter-Process Communication

CoreServices

ImageI/O

Accelerate

Security

SystemConfiguration

International Components for Unicode

DictionaryServices

Xcode Toolchain

Third-Party Tools

CocoaPods