Swizzle Dec 31st, 2013 A new concept to me: http://stackoverflow.com/questions/20775670/set-ivar-value-from-category Here is a summary: 1 2 3 original = class_getInstanceMethod([ClassA class], @selector(setImportantProperty:)); swizzled = class_getInstanceMethod([ClassA class], @selector(alternative_setImportantProperty:)); method_exchangeImplementations(original, swizzled); `