Giving The Root Row Of An Outline View A Different Background Color.

Question

I have some code to do this (which is below) but I get one error stopping it from working and the error is ''MyOutlineView' may not respond to '-objectArray'', it says that it needs to be declared but I don't know what code I should use in the Header File to declare it.

The Code:

- (void) outlineView: (NSOutlineView *) aView
willDisplayCell: (id) aCell
forTableColumn: (NSTableColumn *)aColumn
item: (id) anItem
{
id rootObj = anItem;
unsigned row = [aView rowForItem:anItem];

[aCell setDrawsBackground: YES];

while ([aView levelForRow:row] != 0) {
row --;
rootObj = [aView itemAtRow:row];
}

// The colours here are foul and ugly. Use something else, for
// God's sake!
if ([[self objectArray] indexOfObject:rootObj] % 2)
[aCell setBackgroundColor: [NSColor yellowColor]];
else
[aCell setBackgroundColor: [NSColor blueColor]];
}

Answer 1

Is objectArray an instance variable of MyOutlineView? If so, just access it directly, like this:

if( [objectArray indexOfObject:rootObj] % 2 )
...

The code [self objectArray] is trying to call a method called objectArray, not reference the ivar objectArray.

Edit: The above assumes that objectArray is an instance variable of MyOutlineView, like:

@interface MyOutlineView {
    NSArray* objectArray;
}

Answer 2

I'm not sure that I am 100% sure of what you are trying to do here, but it does seem to me that you could simply replace this:

  if ([[self objectArray] indexOfObject:rootObj] % 2)
    [aCell setBackgroundColor: [NSColor yellowColor]];
  else
    [aCell setBackgroundColor: [NSColor blueColor]];

with

if ([aView rowForItem:rootObj] % 2) 
  [aCell setBackgroundColor: [NSColor yellowColor]];
else
  [aCell setBackgroundColor: [NSColor blueColor]];

Your rootObj is an item in the outline just as anItem is and this should tell you what row that root item is in. Of course, maybe I don't understand what you're trying to find there.