iOS: Categories in a Static Library Not Working?

Grrr…if you have category methods in a static library and those methods don’t seem to exist at runtime (unrecognized selector sent to class 0x...), first make sure that your project target is passing the -ObjC flag to the linker (in Other linker flags). If that doesn’t fix the issue, change the -ObjC flag to -all_load. Details from Apple in this Technical Q&A.

You might also try using nm to see if your category methods are being properly compiled into your .o file. If they are, next invoke nm on your application binary. If they exist in the binary, the linking is happening properly and you’re likely just misspelling the method name or something or that sort.