NSOutlineView drag promises with directories

NSOutlineView drag promises with directories

How does one implement an NSOutlineViewDataSource to allow dragging
directories that do not exist in the file system at the time of dragging
to the Finder? I have searched and searched and read a ton of the
documentation, but have had great difficulty finding anything of value
that works. I use a custom data source that manages a file system-like
tree, and all the items are instances of a class that keeps track of its
path. I would like to be able to drag files and directories out of the
outline view into the Finder.
I have:
- (BOOL)outlineView:(NSOutlineView *)outlineView writeItems:(NSArray
*)items toPasteboard:(NSPasteboard *)pasteboard {
NSMutableArray *types = [NSMutableArray array];
for (JOItemInfo *itemInfo in items) {
NSString *extension = itemInfo.name.pathExtension;
if (extension.length > 0) [types addObject:extension];
}
[pasteboard declareTypes:@[(__bridge_transfer NSString
*)kPasteboardTypeFileURLPromise] owner:self];
[pasteboard setPropertyList:types forType:(__bridge_transfer
NSString *)kPasteboardTypeFileURLPromise];
DDLogInfo(@"Wrote types %@ to pasteboard %@ for key %@", types,
pasteboard, (__bridge_transfer NSString
*)kPasteboardTypeFileURLPromise);
return YES;
}
and an implementation of
-outlineView:namesOfPromisedFilesDroppedAtDestination:forDraggedItems:
that writes the items inside of the given path. This works in that I can
drag items out to the Finder, but when I let go nothing else happens, and
the -...namesOfPromisedFilesDropped... method isn't even called. Also,
[self.outlineView
setDraggingDestinationFeedbackStyle:NSTableViewDraggingDestinationFeedbackStyleRegular];
[self.outlineView setDraggingSourceOperationMask:NSDragOperationNone
forLocal:YES];
[self.outlineView setDraggingSourceOperationMask:NSDragOperationCopy
forLocal:NO];
is in my -awakeFromNib. The if (extension.length > 0) ... was based on an
example I found somewhere, but it was dated, and the documentation says to
return an extension, so I think that is appropriate. Personally, I find
the documentation for this whole area very lacking, especially in regard
to an NSOutlineView. Thanks!
Update: I changed (__bridge_transfer NSString
*)kPasteboardTypeFileURLPromise to NSFilesPromisePboardType, and I can now
drag files (with an extension at least) and they can be dropped
successfully in the Finder. (I had used the former b/c the documentation
for the latter recommended that, but they do not have the same effect.)
Directories and files without an extension still can't be dragged.