Re: NSSortDescriptor not working with array of custom classes

FROM : Ken Tozier
DATE : Mon Nov 05 00:25:24 2007

On Nov 4, 2007, at 6:05 PM, Shawn Erickson wrote:

> Can you post a complete code sample that shows the problem you are 
> reporting. We are having to guess at what your class(es) involved 
> really look like. You can simplify it down to some thing that shows 
> the issue you having.


That last post was pretty much where the problem is, but here's a 
couple of other methods to flesh it in

// page view class is defined like so:
@interface PMPageView : NSView
{
   PMPageModel                *model;
   
   BOOL                    isEven,
                           active,
                           selected;
                           
   KIntegerField            *pageNumberField;
                           
   NSColor                    *fillColor;
                           
   int                        pageNumber,
                           clickCount;
   
   unsigned int            selectionModifiers;
   
   NSRect                    intFrame;
}

/* if uncommented, sorting works but it just seems silly to have to 
do this
- (id) valueForKeyPath:(id) inKey
{
   if ([inKey isEqualToString: @"model.pageNumber"])
       return [model pageNumber];
   else
       return [super valueForKeyPath: inKey];
}
*/

// page model class is defined like so:
@interface PMPageModel : NSObject
{
   PMPublicationModel        *publication;
   NSMutableDictionary        *pageRecord;
   PHPInvocation            *invocation;
   NSString                *color;
}


// User types in an NSTextFiled to change the number of a page. 
Custom page matrix superview receives a notification in it's 
"observeValueForKeyPath" method

- (void) observeValueForKeyPath:(NSString *) inKeyPath
           ofObject:(id) inObject
           change:(NSDictionary *) inChange
           context:(void *) inContext
{
   if ([inKeyPath isEqualToString: @"pageRecord.page_number"])
   {
       [self handlePageNumberChange];
   }
}

// observeValueForKeyPath calls handler for the page number change
- (void) handlePageNumberChange
{
   [self sortPageViews];
       
   // update the records mod date (for observers)
   [self setRecordsModified: recordsModified + 1];
}

// handlePageNumberChange calls "sortPageViews" method (Note: 
sortPageViews is used by other methods so it's been factored into its 
own method)

- (void) sortPageViews
{
   NSLog(@"pages before sortine: %@, class: %@", pages, [pages class]);
   NSMutableArray        *desc    = [[NSMutableArray alloc] init];
   
   // these all print valid values to the run log
   NSLog(@"first page: %@", [pages objectAtIndex: 0]);
   NSLog(@"direct call page view accessor: %i", [[pages objectAtIndex: 
0] pageNumber]);
   NSLog(@"direct call model accessor: %@", [[[pages objectAtIndex: 0] 
model] pageNumber]);
   NSLog(@"direct call model raw accessor: %@", [[[[pages 
objectAtIndex: 0] model] valueForKeyPath: @"pageRecord"] 
objectForKey: @"page_number"]);
   NSLog(@"direct call model raw accessor 2: %@", [[[pages 
objectAtIndex: 0] model] valueForKeyPath: @"pageRecord.page_number"]);
   
   // these all print null
   NSLog(@"page view accessor: %@", [[pages objectAtIndex: 0] 
valueForKeyPath: @"pageNumber"]);
   NSLog(@"model accessor: %@", [[pages objectAtIndex: 0] 
valueForKeyPath: @"model.pageNumber"]);
   NSLog(@"model raw accessor: %@", [[pages objectAtIndex: 0] 
valueForKeyPath: @"model.pageRecord.page_number"]);
   
   // all of these fail unless I define "
   [desc addObject: [[NSSortDescriptor alloc] initWithKey: 
@"pageNumber" ascending: YES]];
   //[desc addObject: [[NSSortDescriptor alloc] initWithKey: 
@"model.pageNumber" ascending: YES]];
   //[desc addObject: [[NSSortDescriptor alloc] initWithKey: 
@"model.pageRecord.page_number" ascending: YES]];
   //[desc addObject: [[NSSortDescriptor alloc] initWithKey: 
@"model.pageNumber" ascending: YES]];
       
   NSArray                *sortedCells        = [pages sortedArrayUsingDescriptors: desc];
   
   NSLog(@"pages after sortine: %@", sortedCells);
   
   [pages release];
   pages                = [[sortedCells mutableCopy] retain];
   
   [self updateCellFramesWithWidth: [self frame].size.width
       forceUpdate: YES];
}

Ken