You're happily writing code one day, click Build, and suddenly the dreaded warning appears: warning: no '-fooMessage' method found (Messages without a matching method signature will be assumed to return 'id' and accept '...' as arguments.) You double-check your code and your method name is correct, so you shrug and move on. A few hours later, your program starts misbehaving strangely. What's going on? Today, I'll explore the mysterious world of Objective-C method signature mismatches, a topic suggested by an anonymous reader.

Welcome to another Friday Q&A, where all references are strong and all values are above average. This week I'm going to talk about how to write macros and functions that take variable arguments in C, as suggested by Damien Sorresso.