Drag & drop support for OPML files

baRSS/Core Data/FeedGroup+Ext.h

@@ -39,13 +39,13 @@ typedef NS_ENUM(int16_t, FeedGroupType) {
 
 + (instancetype)newGroup:(FeedGroupType)type inContext:(NSManagedObjectContext*)context;
 - (void)setParent:(FeedGroup *)parent andSortIndex:(int32_t)sortIndex;
+- (void)setSortIndexIfChanged:(int32_t)sortIndex;
 - (void)setNameIfChanged:(NSString*)name;
 - (NSMenuItem*)newMenuItem;
 // Handle children and parents
 - (NSString*)indexPathString;
 - (NSArray<FeedGroup*>*)sortedChildren;
 - (NSMutableArray<FeedGroup*>*)allParents;
-- (BOOL)iterateSorted:(BOOL)ordered overDescendantFeeds:(void(^)(Feed *feed, BOOL* cancel))block;
 // Printing
 - (NSString*)readableDescription;
 @end

baRSS/Core Data/FeedGroup+Ext.m

@@ -58,11 +58,15 @@
 + (instancetype)newGroup:(FeedGroupType)type inContext:(NSManagedObjectContext*)moc {
 	FeedGroup *fg = [[FeedGroup alloc] initWithEntity: FeedGroup.entity insertIntoManagedObjectContext:moc];
 	fg.type = type;
-	if (type == FEED)
-		fg.feed = [Feed newFeedAndMetaInContext:moc];
+	switch (type) {
+		case GROUP:     break;
+		case FEED:      fg.feed = [Feed newFeedAndMetaInContext:moc]; break;
+		case SEPARATOR: fg.name = @"---"; break;
+	}
 	return fg;
 }
 
+/// Set @c parent and @c sortIndex. Also if type is @c FEED calculate and set @c indexPath string.
 - (void)setParent:(FeedGroup *)parent andSortIndex:(int32_t)sortIndex {
 	self.parent = parent;
 	self.sortIndex = sortIndex;
@@ -70,6 +74,16 @@
 		[self.feed calculateAndSetIndexPathString];
 }
 
+/// Set @c sortIndex of @c FeedGroup. Iterate over all @c Feed child items and update @c indexPath string.
+- (void)setSortIndexIfChanged:(int32_t)sortIndex {
+	if (self.sortIndex != sortIndex) {
+		self.sortIndex = sortIndex;
+		[self iterateSorted:NO overDescendantFeeds:^(Feed *feed, BOOL *cancel) {
+			[feed calculateAndSetIndexPathString];
+		}];
+	}
+}
+
 /// Set @c name attribute but only if value differs.
 - (void)setNameIfChanged:(NSString*)name {
 	if (![self.name isEqualToString: name])