...Its purpose is to expose class interfaces—methods, properties, ivars, protocols—that are not documented by Apple, making it easier to explore system behavior and reverse-engineer APIs. The headers are generated by inspecting binaries and metadata, then organized by framework so developers can browse relationships and inheritance hierarchies. This is invaluable for research, debugging, and tooling where you need to understand what UIKit, Foundation, or lower-level frameworks are actually doing under the hood. The project encourages read-only exploration; code using private APIs is generally unsuitable for App Store distribution. ...