How to discard CoreData changes in one object when RKObjectManager failed to post object

Question

how to discard CoreData changes made to an instance of NSManagedObject when POST/PUT request of this object fails in RKObjectManager?

NSManagedObject *object = ...;
[object setValue:@"test" forKey: @"test"];
[[RKObjectManager sharedManager] postObject:object 
                                 parameters:nil 
                                    success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) { NSLog(@"success, nothing to do"); }
                                    failure:^(RKObjectRequestOperation *operation, NSError *error) { 
  // I want to discard changes made to object here 
}

UPDATE: RestKit 0.20

Answer 1

I know nothing about RKObjectManager, but in order to discard changes to NSManagedObject instance you could call:

[object.managedObjectContext refreshObject:object mergeChanges:NO]

This will discard all changes and turn the object into fault.

see here

Answer 2

Swift solution:

import CoreData

extension NSManagedObject {
    func cancelChanges() {
        managedObjectContext?.refresh(self, mergeChanges: false)
    }
}

Using:

object.cancelChanges()