Aspects
Library for aspect oriented programming in Objective-C and Swift
... (February 2019) I STRICTLY DO NOT RECOMMEND TO USE Aspects IN PRODUCTION CODE. We use it for partial test mocks in, PSPDFKit, an iOS PDF framework that ships with apps like Dropbox or Evernote, it's also very useful for quickly hacking something up. Aspects uses _objc_msgForward which causes issues with other code that uses message forwarding.