unsigned int ivarCount = 0;    Ivar *ivars = class_copyIvarList([User class], &ivarCount);        for (unsigned int i = 0; i < ivarCount; i++) {        Ivar ivar = ivars[i];        const char *name = ivar_getName(ivar);        NSLog(@"ivar name = %@", [NSString stringWithUTF8String:name]);                ptrdiff_t offset = ivar_getOffset(ivar);        NSLog(@"ivar offset = %zd", offset);                const char *encoding = ivar_getTypeEncoding(ivar);        NSLog(@"ivar type = %@", [NSString stringWithUTF8String:encoding]);    }    free(ivars);        unsigned int methodCount = 0;    Method *methods = class_copyMethodList([User class], &methodCount);        for (unsigned int i = 0; i < methodCount; i++) {        Method method = methods[i];                SEL sel = method_getName(method);        NSLog(@"method name = %@", NSStringFromSelector(sel));                char *returnType = method_copyReturnType(method);        NSLog(@"method returnType = %@", [NSString stringWithUTF8String:returnType]);        free(returnType);                const char *typeEncoding = method_getTypeEncoding(method);        NSLog(@"method typeEncoding = %@", [NSString stringWithUTF8String:typeEncoding]);                unsigned int argumentCount = method_getNumberOfArguments(method);        for (unsigned int i = 0; i < argumentCount; i++) {            char *argumentType = method_copyArgumentType(method, i);            NSLog(@"method argumentType = %@", [NSString stringWithUTF8String:argumentType]);            free(argumentType);        }    }    free(methods);        unsigned int propertyCount = 0;    objc_property_t *propertys = class_copyPropertyList([User class], &propertyCount);        for (unsigned int i = 0; i < propertyCount; i++) {        objc_property_t property = propertys[i];                const char *name = property_getName(property);        NSLog(@"property name = %@", [NSString stringWithUTF8String:name]);                unsigned int attCount = 0;        objc_property_attribute_t *attributes = property_copyAttributeList(property, &attCount);        for (unsigned int i = 0; i < attCount; i++) {            objc_property_attribute_t att = attributes[i];            NSLog(@"attribute name = %@", [NSString stringWithUTF8String:att.name]);            NSLog(@"attribute value = %@", [NSString stringWithUTF8String:att.value]);        }        free(attributes);    }    free(propertys);