[code ]#import

@interface CTCoreDataUndoWindow : NSWindow {

NSButton* _okButton;
NSButton* _cancelButton;
id _target;
SEL _ok;
SEL _cancel;

}

@property (readwrite, retain) IBOutlet NSButton* okButton; @property (readwrite, retain) IBOutlet NSButton* cancelButton;

• (void)showOnWindow:(NSWindow*)w;

@end [/code]

[code]

import "CTCoreDataUndoWindow.h"

@implementation CTCoreDataUndoWindow

@synthesize okButton = _okButton; @synthesize cancelButton = _cancelButton;

• (NSUndoManager *)windowWillReturnUndoManager:(NSWindow *)window { return [self undoManager]; }

• (NSUndoManager*)undoManager { return [[self.delegate managedObjectContext] undoManager]; }

• (void)showOnWindow:(NSWindow*)w { [[self undoManager] beginUndoGrouping]; [self.okButton setAction:@selector(okSheet:)]; [self.cancelButton setAction:@selector(cancelSheet:)]; [self.okButton setTarget:self]; [self.cancelButton setTarget:self]; [NSApp beginSheet:self modalForWindow:w modalDelegate:nil didEndSelector:NULL contextInfo:NULL]; }

• (void)cancelSheet:(id)sender { [[self undoManager] endUndoGrouping]; [[self undoManager] undo]; [self orderOut:self]; [NSApp endSheet:self]; }

• (void)okSheet:(id)sender { [[self undoManager] endUndoGrouping]; [[self undoManager] setActionName:@"Object edit"]; [self orderOut:self]; [NSApp endSheet:self]; }

@end [/code]

There is always more than one way to solve an issue. As I said before I would not recommend yours as an optimal solution. Perhaps if your context is small it would be light enough to use but I would certainly not do it that way.

If it works for you then great — Enjoy it!

http://developer.apple.com/documentation/Cocoa/Conceptual/NSPersistentDocumentTutorial/08_CreationSheet/chapter_9_section_1.html#//apple_ref/doc/uid/TP40001799-CH284-SW2

If the possibility of a redo is that much of an issue I would recommend creating an independent undo manager for the sheet that tracks all of the changes in that sheet. Much cheaper than copying all of the managed objects and since the sheet is destroyed upon completion there is no chance of the redo issue.

There’s also the easier option that if you don’t want undo support in the sheet, you can disable undo registration while the sheet is running and re-enable it after the user dismisses it.

This would allow the user to redo the changes in the sheet without bringing it back up if you are using the same NSManagedObjectContext for the sheet and the document window. Unfortunately, NSUndoManager doesn’t have a method for removing only the top item from either stack.

What I usually end up doing is to create a new NSManagedObjectContext for the sheet (which involves non-trivial copying of the edited managed object to and from the 2 contexts). It’s non-trivial because you have to think about what copying means to relationships in your object model and there’s also the whole thing about NSManagedObjectIDs not being fetchable from another context if they are temporary in the first context.