A smart macro for getting a key string for an Objective-C property. Will give you a proper compilation error if something is wrong :)

Objective-C property key macro

#define KEY(Class, key)   ( YES ? @#key : ^{ (void)((Class *)[[Class alloc] init]).key; return @""; }() )

/*
  Usage:
  KEY(UIViewController, navigationItem) - returns @"navigationItem"
  KEY(UIView, frame) - returns @"frame"
  KEY(UIView, tag) - returns @"tag"
  KEY(UIView, foobar) - compilation error!
*/