objc_direct is a compiler feature that turns objective c methods into unexported C functions, direct methods can therefore neither be hooked or called from within tweaks. Many system binaries started using it in iOS 14.
libundirect is a developer library that is able to patchfind direct methods (with developer supplied data to search for) and rebind them back to the objective c methods, this allows tweaks to be fully backwards compatible with non objc_direct binaries with minimal effort.
Documentation and source code available
on GitHub
This is a developer package. No app is added to the homescreen, and no screenshots for this item.
dylib installed to /usr/lib