NSOutlineView Changing group row color - objective-c

Question

In my NSOutlineview i am using custom cell which is subclassed from NSTextFieldCell,
I need to draw different color for group row and for normal row, when its selected,
To do so, i have done following ,
-(id)_highlightColorForCell:(NSCell *)cell
{
return [NSColor colorWithCalibratedWhite:0.5f alpha:0.7f];
}
Yep i know its private API, but i couldn't found any other way,
this is working very well for Normal Row, but no effect on Group Row, Is there any way to change the group color,
Kind Regards
Rohan

Answer 1

You can actually do this without relying on private API's, at least if your willing to require Mac OS X 10.4 or better.
Put the following in your cell subclass:
- (NSColor *)highlightColorWithFrame:(NSRect)cellFrame inView:(NSView *)controlView
{
// Returning nil circumvents the standard row highlighting.
return nil;
}
And then subclass the NSOutlineView and re-implement the method, - (void)highlightSelectionInClipRect:(NSRect)clipRect;
Here's an example that draws one color for non-group rows and another for group rows
- (void)highlightSelectionInClipRect:(NSRect)clipRect
{
NSIndexSet *selectedRowIndexes = [self selectedRowIndexes];
NSRange visibleRows = [self rowsInRect:clipRect];
NSUInteger selectedRow = [selectedRowIndexes firstIndex];
while (selectedRow != NSNotFound)
{
if (selectedRow == -1 || !NSLocationInRange(selectedRow, visibleRows))
{
selectedRow = [selectedRowIndexes indexGreaterThanIndex:selectedRow];
continue;
}
// determine if this is a group row or not
id delegate = [self delegate];
BOOL isGroupRow = NO;
if ([delegate respondsToSelector:#selector(outlineView:isGroupItem:)])
{
id item = [self itemAtRow:selectedRow];
isGroupRow = [delegate outlineView:self isGroupItem:item];
}
if (isGroupRow)
{
[[NSColor alternateSelectedControlColor] set];
} else {
[[NSColor secondarySelectedControlColor] set];
}
NSRectFill([self rectOfRow:selectedRow]);
selectedRow = [selectedRowIndexes indexGreaterThanIndex:selectedRow];
}
}