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
    }
}