Open Radar

 
Summary:
Wrong grouping level of NSUndoManager during the NSUndoManagerWillUndoChangeNotification and
NSUndoManagerDidUndoChangeNotification

Steps to Reproduce:
If I do [NSUndoManager undoNestedGroup] in a nested group, I get always 0 for grouping level if I listen to NSUndoManagerWillUndoChangeNotification or NSUndoManagerDidUndoChangeNotification. With that I cannot distinguish
between undo of a nested group or a complete action. Here is a little test case:

#import <Foundation/Foundation.h>

@interface TestObject : NSObject

@property (nonatomic) NSUInteger value;

@end

@implementation TestObject

- (void)test {
	
	NSUndoManager *undoManger = [[NSUndoManager alloc] init];
	undoManger.groupsByEvent = NO;
	
	NSNotificationCenter *center = [NSNotificationCenter defaultCenter];
	[center addObserverForName:NSUndoManagerWillCloseUndoGroupNotification
						object:undoManger
						 queue:nil
					usingBlock:^(NSNotification *note) {
						NSLog(@"Will close group at level %li", undoManger.groupingLevel);
					}];
	[center addObserverForName:NSUndoManagerDidCloseUndoGroupNotification
						object:undoManger
						 queue:nil
					usingBlock:^(NSNotification *note) {
						NSLog(@"Did close group at level %li", undoManger.groupingLevel);
					}];
	[center addObserverForName:NSUndoManagerWillUndoChangeNotification
						object:undoManger
						 queue:nil
					usingBlock:^(NSNotification *note) {
						NSLog(@"Will undo at level %li", undoManger.groupingLevel);
					}];
	[center addObserverForName:NSUndoManagerDidUndoChangeNotification
						object:undoManger
						 queue:nil
					usingBlock:^(NSNotification *note) {
						NSLog(@"Did undo at level %li", undoManger.groupingLevel);
					}];
	
	NSLog(@"Set value to 1");
	self.value = 1;
	
	NSAssert(undoManger.groupingLevel == 0, @"Wrong grouping level: %li", undoManger.groupingLevel);
	
	NSLog(@"Begin group");
	[undoManger beginUndoGrouping];
	
	NSLog(@"Set value to 2");
	[[undoManger prepareWithInvocationTarget:self] setValue:self.value];
	self.value = 2;
	
	NSAssert(undoManger.groupingLevel == 1, @"Wrong grouping level: %li", undoManger.groupingLevel);
	NSAssert(self.value == 2, @"Wrong value: %li", self.value);
	
	NSLog(@"Begin group");
	[undoManger beginUndoGrouping];
	
	NSLog(@"Set value to 3");
	[[undoManger prepareWithInvocationTarget:self] setValue:self.value];
	self.value = 3;
	
	NSAssert(undoManger.groupingLevel == 2, @"Wrong grouping level: %li", undoManger.groupingLevel);
	NSAssert(self.value == 3, @"Wrong value: %li", self.value);
	
	NSLog(@"End group");
	[undoManger endUndoGrouping];
	
	NSAssert(undoManger.groupingLevel == 1, @"Wrong grouping level: %li", undoManger.groupingLevel);
	NSAssert(self.value == 3, @"Wrong value: %li", self.value);
	
	NSLog(@"Undo group");
	[undoManger undoNestedGroup];
	
	NSAssert(undoManger.groupingLevel == 1, @"Wrong grouping level: %li", undoManger.groupingLevel);
	NSAssert(self.value == 2, @"Wrong value: %li", self.value);
	
	NSLog(@"End group");
	[undoManger endUndoGrouping];
	
	NSAssert(undoManger.groupingLevel == 0, @"Wrong grouping level: %li", undoManger.groupingLevel);
	NSAssert(self.value == 2, @"Wrong value: %li", self.value);
	
	NSLog(@"Undo");
	[undoManger undo];
	
	NSAssert(undoManger.groupingLevel == 0, @"Wrong grouping level: %li", undoManger.groupingLevel);
	NSAssert(self.value == 1, @"Wrong value: %li", self.value);
}

@end

int main(int argc, const char * argv[])
{
	@autoreleasepool {
	    TestObject *object = [[TestObject alloc] init];
	    [object test];
	}
    return 0;
}


Expected Results:
I would expect a output with "Will undo at level 1" and a output "Will undo at level 0"

Actual Results:
Both output are at level 0. See following output:

2013-06-06 17:51:22.452 TestUndoManager[68089:303] Set value to 1
2013-06-06 17:51:22.463 TestUndoManager[68089:303] Begin group
2013-06-06 17:51:22.467 TestUndoManager[68089:303] Set value to 2
2013-06-06 17:51:22.473 TestUndoManager[68089:303] Begin group
2013-06-06 17:51:22.476 TestUndoManager[68089:303] Set value to 3
2013-06-06 17:51:22.479 TestUndoManager[68089:303] End group
2013-06-06 17:51:22.482 TestUndoManager[68089:303] Will close group at level 2
2013-06-06 17:51:22.485 TestUndoManager[68089:303] Did close group at level 1
2013-06-06 17:51:22.489 TestUndoManager[68089:303] Undo group
2013-06-06 17:51:22.492 TestUndoManager[68089:303] Will undo at level 0
2013-06-06 17:51:22.494 TestUndoManager[68089:303] Did undo at level 0
2013-06-06 17:51:22.500 TestUndoManager[68089:303] End group
2013-06-06 17:51:22.502 TestUndoManager[68089:303] Will close group at level 1
2013-06-06 17:51:22.504 TestUndoManager[68089:303] Did close group at level 0
2013-06-06 17:51:22.505 TestUndoManager[68089:303] Undo
2013-06-06 17:51:22.506 TestUndoManager[68089:303] Will undo at level 0
2013-06-06 17:51:22.508 TestUndoManager[68089:303] Did undo at level 0

Notes:
At the moment I have no way to distinguish between an undo of a nested group and a normal undo.