I used to maintain a Finder plugin that added icon overlays to files, and added menu items to right-click menus.
It worked by injecting code into Finder at runtime, and then swapping method implementations for various classes. (Mac developers call this swizzling.)
We basically had to reverse engineer Finder every time Apple shipped a new version of MacOS. Later, as the process grew more common, we had to add tricks to make sure that we could work smoothly with other similar plugins.
I jumped for joy when Apple released the Finder Extension API!
It worked by injecting code into Finder at runtime, and then swapping method implementations for various classes. (Mac developers call this swizzling.)
We basically had to reverse engineer Finder every time Apple shipped a new version of MacOS. Later, as the process grew more common, we had to add tricks to make sure that we could work smoothly with other similar plugins.
I jumped for joy when Apple released the Finder Extension API!