How to correctly display the enumerated objects using NSTreeController - objective-c

Question

I'm trying to understand how to use NSTreeController. When I added a method (segment of the SourceView example's class and method are provided below) to iterate the contents of the directory, which is transmitted through NSTreeController to the NSOutlineView. But, NSOutlineView displays only the first objects (root objects) (you can be seen it on the schemes below).
Class NSTreeController Methods:
- (void)performAddChild:(TreeAdditionObj *)treeAddition {
if ([[treeController selectedObjects] count] > 0) {
// we have a selection
if ([[[treeController selectedObjects] objectAtIndex:0] isLeaf]) {
// trying to add a child to a selected leaf node, so select its parent for add
[self selectParentFromSelection];
}
}
// find the selection to insert our node
NSIndexPath *indexPath;
if ([[treeController selectedObjects] count] > 0) {
// we have a selection, insert at the end of the selection
indexPath = [treeController selectionIndexPath];
indexPath = [indexPath indexPathByAddingIndex:[[[[treeController selectedObjects] objectAtIndex:0] children] count]];
} else {
// no selection, just add the child to the end of the tree
indexPath = [NSIndexPath indexPathWithIndex:[contents count]];
}
// create a leaf node
BaseNode *node = [[BaseNode alloc] initLeaf];
node.urlString = [treeAddition nodeURL];
if ([treeAddition nodeURL]) {
if ([[treeAddition nodeURL] length] > 0) {
// the child to insert has a valid URL, use its display name as the node title
if ([treeAddition nodeName])
node.nodeTitle = [treeAddition nodeName];
else
node.nodeTitle = [[NSFileManager defaultManager] displayNameAtPath:[node urlString]];
}
}
// the user is adding a child node, tell the controller directly
[treeController insertObject:node atArrangedObjectIndexPath:indexPath];
// adding a child automatically becomes selected by NSOutlineView, so keep its parent selected
if ([treeAddition selectItsParent])
[self selectParentFromSelection];
}
- (void)addChild:(NSString *)url withName:(NSString *)nameStr selectParent:(BOOL)select {
TreeAdditionObj *treeObjInfo = [[TreeAdditionObj alloc] initWithURL:url
withName:nameStr
selectItsParent:select];
if (buildingOutlineView) {
// add the child node to the tree controller, but on the main thread to avoid lock ups
[self performSelectorOnMainThread:#selector(performAddChild:)
withObject:treeObjInfo
waitUntilDone:YES];
} else {
[self performAddChild:treeObjInfo];
}
}
Method for displaying enumerated objects of the directory:
- (void)addFinderSection {
[self addFolder:#"FINDER FILES"];
NSError *error = nil;
NSEnumerator *urls = [[[NSFileManager defaultManager] contentsOfDirectoryAtURL:self.url includingPropertiesForKeys:[NSArray arrayWithObjects: nil] options:(NSDirectoryEnumerationSkipsHiddenFiles) error:&error] objectEnumerator];
for (NSURL *url in urls) {
BOOL isDirectory;
if ([[NSFileManager defaultManager] fileExistsAtPath:[url path] isDirectory:&isDirectory]) {
if (isDirectory) {
if (![[NSWorkspace sharedWorkspace] isFilePackageAtPath:[url path]]) {
NSLog(#"IS DIRECTORY %#", url);
[self addChild:[url path] withName:NO selectParent:YES];
}
} else {
NSLog(#"IS FIlE %#", url);
[self addChild:[url path] withName:NO selectParent:YES];
}
}
}
[self selectParentFromSelection];
}
My mistake is probably that is NSTreeController does not differentiate between the simple objects (files) and the directories (folders).
However, when I fill NSOutlineView without NSTreeController, all content is displayed are correctly:
NOTE: If use method addFolder: (in SourceView example it used for create parent groups for other objects) then, every next object displayed as a subgroup of previous.
Can you help me to correctly display the folder contents in these methods?