outlineView:objectValueForTableColumn:byItem: not called

Question

I'm trying to create a source list for a new program and I'm having a little issue using a view-based NSOutlineView. My code works fine using a cell-based NSOutlineView so I'm a little confused about what is happening.

Here is my code for the delegate and data source:

#pragma mark -
#pragma mark NSOutlineView Delegate

- (BOOL)outlineView:(NSOutlineView *)outlineView isGroupItem:(id)item {
    return (item == nil) ? YES : [(SourceListNode *)item groupItem];
}

- (id)outlineView:(NSOutlineView *)outlineView viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item {
    if ([(SourceListNode *)item groupItem]) {
        return [outlineView makeViewWithIdentifier:@"HeaderCell" owner:self];
    }
    else {
        return [outlineView makeViewWithIdentifier:@"DataCell" owner:self];
    }
}

#pragma mark -
#pragma mark NSOutlineView Data Source

- (NSInteger)outlineView:(NSOutlineView *)outlineView numberOfChildrenOfItem:(id)item {
    return (item == nil) ? [sourceListNodes count] : [(SourceListNode *)item numberOfChildren];
}

- (BOOL)outlineView:(NSOutlineView *)outlineView isItemExpandable:(id)item {
    return (item == nil) ? YES : ([(SourceListNode *)item numberOfChildren] > 0);
}

- (id)outlineView:(NSOutlineView *)outlineView child:(NSInteger)index ofItem:(id)item {
    return (item == nil) ? [sourceListNodes objectAtIndex:index] : [(SourceListNode *)item childAtIndex:index];
}

- (id)outlineView:(NSOutlineView *)outlineView objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)item {
    return [(SourceListNode *)item name];
}

When I run this through the debugger it see that outlineView:objectValueForTableColumn:byItem: does not execute. The result is an outline view with no text. The correct cells are created and I am able to select them and expand them. What am I missing?

UPDATE: I deleted my source list in IB, added a new one, and connected it to my controller object. The results were better, but the header cells had the text "HEADER CELL" and the child cells had "Table View Cell".

I ran the program through the debugger again and this time outlineView:objectValueForTableColumn:byItem: was executed. It did not populate the text of the cell though.

I then updated outlineView:viewForTableColumn:item: as follows:

- (id)outlineView:(NSOutlineView *)outlineView viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item {
    NSTableCellView *result;
    if ([(SourceListNode *)item groupItem]) {
        result = [outlineView makeViewWithIdentifier:@"HeaderCell" owner:self];
    }
    else {
        result = [outlineView makeViewWithIdentifier:@"DataCell" owner:self];
    }

    [[result textField] setStringValue:[(SourceListNode *)item name]];

    return result;
}

Now everything works as expected.

So in short, I have solved my problem. However, I now have another question. What is the purpose of outlineView:objectValueForTableColumn:byItem: for view-base outline views? It executes, but does not appear to do anything.

Answer 1

View-based is a tad different than cell-based.

All that is different is replacing the "id" return value to "NSView".

Change this:

- (id)outlineView:(NSOutlineView *)outlineView viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item

To this:

- (NSView *)outlineView:(NSOutlineView *)outlineView viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item

This is given the assumption you are running 10.7, and you are actually going to return an NSView.