Re-wrote sorting code to be smaller and easier to understand

Shared/Timeline/ArticleSorter.swift

@@ -32,28 +32,21 @@ struct ArticleSorter {
 		
 	private static func sortedByFeedName<T: SortableArticle>(articles: [T],
 															 sortByDateDirection: ComparisonResult) -> [T] {
-		// Group articles by feed - feed ID is used to differentiate between
+		// Group articles by "feed-feedID" - feed ID is used to differentiate between
 		// two feeds that have the same name
-		var groupedArticles = Dictionary(grouping: articles) { "\($0.sortableName.lowercased())-\($0.sortableFeedID)" }
-		
-		// Sort the articles within each group
-		for tuple in groupedArticles {
-			groupedArticles[tuple.key] = sortedByDate(articles: tuple.value,
-													  sortDirection: sortByDateDirection)
+		let groupedArticles = Dictionary(grouping: articles) { "\($0.sortableName.lowercased())-\($0.sortableFeedID)" }
+		return groupedArticles
+			.sorted { $0.key < $1.key }
+			.flatMap { (tuple) -> [T] in
+				let (_, articles) = tuple
+				
+				return sortedByDate(articles: articles, sortDirection: sortByDateDirection)
 		}
-		
-		// Flatten the articles dictionary back into an array sorted by feed name
-		var sortedArticles: [T] = []
-		for feedName in groupedArticles.keys.sorted() {
-			sortedArticles.append(contentsOf: groupedArticles[feedName] ?? [])
-		}
-		
-		return sortedArticles
 	}
 	
 	private static func sortedByDate<T: SortableArticle>(articles: [T],
 														 sortDirection: ComparisonResult) -> [T] {
-		let articles = articles.sorted { (article1, article2) -> Bool in
+		return articles.sorted { (article1, article2) -> Bool in
 			if article1.sortableDate == article2.sortableDate {
 				return article1.sortableArticleID < article2.sortableArticleID
 			}
@@ -63,7 +56,6 @@ struct ArticleSorter {
 			
 			return article1.sortableDate < article2.sortableDate
 		}
-		return articles
 	}
 	
 }