Dynamic NSOutlineView data source

Question

So I have implemented a PXSourceList data source that pretty much is a duplicate of Apple's example of a NSOutlineView data source.

This is how it goes...

- (NSUInteger)sourceList:(PXSourceList*)sourceList numberOfChildrenOfItem:(id)item; {
    if (item == nil) {
        // item is nil so it's part of the very top hierarchy.
        // return how many sections we need.
        return 2;
    }
    else {
        if ([item class] == [TSFileSystemItem class] ) {
            return [item numberOfChildren];
            // if item isn't nil and it's a TSFileSystemItem, then return it's children.
        }
        if ([item class] == [TSWorkspaceItem class]) {
            return 2; // i don't know, random items.
        }
        else {
            NSLog(@"this is a special object.");
        }
    }
}

- (BOOL)sourceList:(PXSourceList *)aSourceList isItemExpandable:(id)item {
    if (item == nil) {
        return YES;
    }
    else {
        // if the number of children of the item is -1
        BOOL gibberhook = ([item numberOfChildren] != -1);
        return gibberhook;
    }
}

-(id)sourceList:(PXSourceList *)aSourceList child:(NSUInteger)index ofItem:(id)item {
    if (item == nil) {
        return [TSFileSystemItem rootItem];
    }
    else {
        return [(TSFileSystemItem *)item childAtIndex:index];
    }
}

- (id)sourceList:(PXSourceList *)aSourceList objectValueForItem:(id)item {
    if (item == nil) {
        return @"/";
    } else {
        if (item == [TSFileSystemItem rootItem]) {
            return PROJECT_FILES;
        }
        else {
            return [item relativePath];
        }
    }
}

The mysterious TSFileSystemItem is from here: https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/OutlineView/Articles/UsingOutlineDataSource.html.

All of this is OK, except I want to divide my source list to have multiple sections (root cells). One displaying a file hierarchy (check) and the other...

Well the other is going to contain a NSMutableArray that I add items to from the other section. Sounds complicated? Better explanation. Click an item from section with file hierarchy, and it is added to the other section.

I have tried to solve this mess with the help of Apple's docs, but I still can't find a simple, efficient, stable way of making 2 sections with the functions I mentioned above. If only it was as easy as configuring a data source for UITableView...

Can anybody kindly help me out?

Answer 1

When the childrenForItem delegate method is called and item in nil, this requests the root of the tree. If you return and array then the tree will have a root node for each element in that array.

- (NSArray *)childrenForItem:(id)item {
    if (item == nil) {
        return [self.rootTreeNode childNodes];
    } else {
        return [item childNodes];
    }
}