void OBJC_ExchangeMethod(Class c, SEL orig, SEL new) { Method origMethod = class_getInstanceMethod(c, orig); Method newMethod = class_getInstanceMethod(c, new); if (class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod))) { class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod)); } else { method_exchangeImplementations(origMethod, newMethod); } }