Welcome to the code repository for iOS and macOS Performance Tuning: Cocoa, Cocoa Touch, Objective-C, and Swift.
Performance tricks and samples Chapter 3 are primarily from MPWFoundation:
The XML parser described is available at https://github.com/mpw/Objective-XML.
The JPJP fork of the JPNG file format can be found here: https://github.com/mpw/JPNG.