On 18 May 2008, at 20:57, Charles Srstka wrote:
Lately, I've been trying to update my stodgy old ways and try to incorporate some of the new technologies Cocoa has picked up over the years when starting new projects (my main app has had to be compatible with older OS X versions, so I haven't had much opportunity to jump into the world of bindings prior to now). One of these is NSTreeController. Unfortunately, I'm having a bit of trouble using figuring out how to do what I want with it.1. The order of the objects in my (non-Core Data) data model is sometimes important, so rather than using the tree controller to add objects, I have been adding them manually by calling the appropriate -insertObject:in<key>atIndex: methods. Okay, that works pretty well, and the objects show up in the NSOutlineView. However, I'd like to select the objects after I insert them. Now, I know where these objects are in the model, but since the order of the objects in the outline view might be different due to the user clicking on one column header or another to sort, and since the index paths sent to the tree controller's -setSelectedIndexPaths: method seem to be based on the interface, not the model, I don't know exactly where these objects are in order to select them. NSTreeController appears to have no -indexPathForObject: method or anything similar - does anyone know a way around this?1a. At first I thought that since I am making a sibling to the currently selected object, I could just get the parent's index path via [[treeController selectionIndexPath] indexPathByRemovingLastIndex], then get the node at that index path and iterate through its -childNodes until I find the one whose - representedObject is the correct model object, but there doesn't seem to be any way to get NSTreeController to give the node (or the model object, for that matter) for an index path. Does anyone else find this a little bizarre
To have an indexPathForObject method you need this:
- (NSArray *)rootNodes;
{
return [[self arrangedObjects] childNodes];
}
// this is a depth-first search
- (NSArray *)flattenedNodes;
{
NSMutableArray *mutableArray = [NSMutableArray array];
for (NSTreeNode *node in [self rootNodes]) {
[mutableArray addObject:node];
if (![[node valueForKey:[self leafKeyPath]] boolValue])
[mutableArray addObjectsFromArray:[node
valueForKey:@"descendants"]];
}
return [[mutableArray copy] autorelease];
}
- (NSTreeNode *)treeNodeForObject:(id)object;
{
NSTreeNode *treeNode = nil;
for (NSTreeNode *node in [self flattenedNodes]) {
if ([node representedObject] == object) {
treeNode = node;
break;
}
}
return treeNode;
}
- (NSIndexPath *)indexPathToObject:(id)object;
{
return [[self treeNodeForObject:object] indexPath];
}
They're all separate methods as I have quite a few extensions on
NSTreeController!
2. Okay, so I've got my objects displaying in an NSOutlineView, and now I'd like to add a search feature. Rather than eliminating the options that don't match, what I want to do is find the object, expand all its ancestors in the outline view so it's visible, and select it. Finding the model object is easy, and doing the rest *would* be easy enough if I weren't using NSTreeController - just climb the family tree, use -rowForItem: for each, expand it, and then use -rowForItem: to get the object and select it. Of course, with NSTreeController we have all these NSTreeNode objects instead of the actual objects themselves in the outline view, so - rowForItem: won't work. Is there any way to find the rows for the various nodes in the family tree of an object without resorting to just iterating through every row in the outline view? Any way to get the tree node for a given model object?
Now you have a treeNode for object you can as the NSOutlineView to expand that item (the NSTreeNode) using -expandItem:
Ive recently written two posts on NSTreeController, the first is non- Core Data the second is with core data but the sample project has a load of extensions that let you do what you want to do. They're at
http://jonathandann.wordpress.com/2008/04/06/using-nstreecontroller/ and http://jonathandann.wordpress.com/2008/05/13/nstreecontroller-and-core-data-sorted/ Hope this helps Jon
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