Monday, June 1, 2020


Peter Steinberger (tweet):

InterposeKit is a modern library to swizzle elegantly in Swift. It is well-documented, tested, written in “pure” Swift 5.2 and works on @objc dynamic Swift functions or Objective-C instance methods. The Inspiration for InterposeKit was a race condition in Mac Catalyst, which required tricky swizzling to fix, I also wrote up implementation thoughts on my blog.

Instead of adding new methods and exchanging implementations based on method_exchangeImplementations, this library replaces the implementation directly using class_replaceMethod. This avoids some of the usual problems with swizzling.

You can call the original implementation and add code before, instead or after a method call.

Peter Steinberger:

imp_implementationWithBlock has no way to undo or deregister the IMP; so once you submitted a block that captures state, you have a permanent memory leak? Oh well.

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