StackOverflow2013

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copied!<p>Wrap your changes in a <code>NSUndoManager beginUndoGrouping</code> and then a <code>NSUndoManager endUndoGrouping</code> followed by a <code>NSUndoManager undo</code>.</p> <p>That is the correct way to roll back changes. The <code>NSManagedObjectContext</code> has its own internal <code>NSUndoManager</code> that you can access.</p> <h2>Update showing example</h2> <p>Because the <code>NSUndoManager</code> is nil by default on Cocoa Touch, you have to create one <strong>and set it into the <code>NSManagedObjectContext first</code></strong>.</p> <pre><code>//Do this once per MOC NSManagedObjectContext *moc = [self managedObjectContext]; NSUndoManager *undoManager = [[NSUndoManager alloc] init]; [moc setUndoManager:undoManager]; [undoManager release], undoManager = nil; //Example of a grouped undo undoManager = [moc undoManager]; NSManagedObject *test = [NSEntityDescription insertNewObjectForEntityForName:@"Parent" inManagedObjectContext:moc]; [undoManager beginUndoGrouping]; [test setValue:@"Test" forKey:@"name"]; NSLog(@"%s Name after set: %@", __PRETTY_FUNCTION__, [test valueForKey:@"name"]); [undoManager endUndoGrouping]; [undoManager undo]; NSLog(@"%s Name after undo: %@", __PRETTY_FUNCTION__, [test valueForKey:@"name"]); </code></pre> <p>Also make sure that your accessors are following the rules of KVO and posting <code>-willChange:</code>, <code>-didChange:</code>, <code>-willAccess:</code> and <code>-DidAccess:</code> notifications. If you are just using <code>@dynamic</code> accessors then you will be fine.</p>

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