Allows folders to efficient add and remove many feeds.

Frameworks/Account/Account.swift

@@ -679,6 +679,15 @@ public final class Account: DisplayNameProvider, UnreadCountProvider, Container,
 		postChildrenDidChangeNotification()
 	}
 	
+	public func removeFeeds(_ feeds: Set<Feed>) {
+		guard !feeds.isEmpty else {
+			return
+		}
+		topLevelFeeds.subtract(feeds)
+		structureDidChange()
+		postChildrenDidChangeNotification()
+	}
+	
 	public func addFeed(_ feed: Feed) {
 		topLevelFeeds.insert(feed)
 		structureDidChange()

Frameworks/Account/Feedly/Refresh/FeedlyCreateFeedsForCollectionFoldersOperation.swift

@@ -82,9 +82,7 @@ final class FeedlyCreateFeedsForCollectionFoldersOperation: FeedlyOperation {
 		// Remove feeds without folders/collections.
 		let feedsAfter = Set(feedsAndFolders.map { $0.0 })
 		let feedsWithoutCollections = feedsBefore.subtracting(feedsAfter)
-		for unmatched in feedsWithoutCollections {
-			account.removeFeed(unmatched)
-		}
+		account.removeFeeds(feedsWithoutCollections)
 		
 		if !feedsWithoutCollections.isEmpty {
 			os_log(.debug, log: log, "Removed %i feeds", feedsWithoutCollections.count)

Frameworks/Account/Folder.swift

@@ -98,6 +98,14 @@ public final class Folder: DisplayNameProvider, Renamable, Container, UnreadCoun
 		postChildrenDidChangeNotification()
 	}
 	
+	public func addFeeds(_ feeds: Set<Feed>) {
+		guard !feeds.isEmpty else {
+			return
+		}
+		topLevelFeeds.formUnion(feeds)
+		postChildrenDidChangeNotification()
+	}
+	
 	public func removeFeed(_ feed: Feed) {
 		topLevelFeeds.remove(feed)
 		postChildrenDidChangeNotification()