Given model object, how to find index path in NSTreeController?

Question

Given model objects that NSTreeController represents, how do you find their index paths in the tree and subsequently select them? This seems to be a blindingly obvious problem, but I can't seem to find any reference to it. Any ideas?

Answer 1

There's no "easy" way, you have to walk the tree nodes and find a matching index path, something like:

Objective-C:

Category

@implementation NSTreeController (Additions)

- (NSIndexPath*)indexPathOfObject:(id)anObject
{
    return [self indexPathOfObject:anObject inNodes:[[self arrangedObjects] childNodes]];
}

- (NSIndexPath*)indexPathOfObject:(id)anObject inNodes:(NSArray*)nodes
{
    for(NSTreeNode* node in nodes)
    {
        if([[node representedObject] isEqual:anObject])
            return [node indexPath];
        if([[node childNodes] count])
        {
            NSIndexPath* path = [self indexPathOfObject:anObject inNodes:[node childNodes]];
            if(path)
                return path;
        }
    }
    return nil; 
}
@end    

Swift:

Extension

extension NSTreeController {

    func indexPathOfObject(anObject:NSObject) -> NSIndexPath? {
         return self.indexPathOfObject(anObject, nodes: self.arrangedObjects.childNodes)
    }

    func indexPathOfObject(anObject:NSObject, nodes:[NSTreeNode]!) -> NSIndexPath? {
         for node in nodes {
            if (anObject == node.representedObject as! NSObject)  {
                 return node.indexPath
            }
            if (node.childNodes != nil) {
                if let path:NSIndexPath = self.indexPathOfObject(anObject, nodes: node.childNodes)
                {
                     return path
                }
            }
        }
        return nil
    }
}

Answer 2

Why not use the NSOutlineView to get the parent items like this:

NSMutableArray *selectedItemArray = [[NSMutableArray alloc] init];

[selectedItemArray addObject:[self.OutlineView itemAtRow:[self.OutlineView selectedRow]]];

while ([self.OutlineView parentForItem:[selectedItemArray lastObject]]) {
  [selectedItemArray addObject:[self.OutlineView parentForItem:[selectedItemArray lastObject]]];
}

NSString *selectedPath = @".";
while ([selectedItemArray count] > 0) {
  OBJECTtype *singleItem = [selectedItemArray lastObject];
  selectedPath = [selectedPath stringByAppendingString:[NSString stringWithFormat:@"/%@", singleItem.name]];
  selectedItemArray removeLastObject];
}

NSLog(@"Final Path: %@", selectedPath);

This will output: ./item1/item2/item3/...

I'm assuming you are looking for a file path here but you can adjust for whatever your data source may represent.