Swizzling in iOS 11 With UIDebuggingInformationOverlay

Where to Go From Here?

You can download the final project from this tutorial.

Crazy tutorial, eh? In this chapter, you spelunked into memory and changed dispatch_once_t tokens as well as Booleans in memory to build a POC UIDebuggingInformationOverlay that’s compatible with iOS 11 while getting around Apple’s newly introduced checks to prevent you from using this class.

Then you used Objective-C’s method swizzling to perform the same actions as well as hook into only a portion of the original method, bypassing several short-circuit checks.

This is why reverse engineering Objective-C is so much fun, because you can hook into methods that are quietly called in private code you don’t have the source for and make changes or monitor what it’s doing.

Still have energy after that brutal chapter? This swizzled code will not work on an ARM64 device. You’ll need to look at the assembly and perform an alternative action for that architecture likely through a preprocessor macro.

If you enjoyed what you learned in the tutorial, why not check out the complete Advanced Apple Debugging & Reverse Engineering book, available in our store?

One thing you can be sure of: after reading this book, you’ll have the tools and knowledge to answer even the most obscure question about your code — or even someone else’s.

Questions? Comments? Come join the forum discussion below!