Rename NavStateController to AppCoordinator because we are redesigning it to be the Coordinator pattern

NetNewsWire.xcodeproj/project.pbxproj

@@ -10,7 +10,7 @@
 		5110AB7822B7BD6200A94F76 /* AddView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5110AB7722B7BD6200A94F76 /* AddView.swift */; };
 		51126DA4225FDE2F00722696 /* RSImage-Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51126DA3225FDE2F00722696 /* RSImage-Extensions.swift */; };
 		5115CAF42266301400B21BCE /* AddContainerViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 51121B5A22661FEF00BC0EC1 /* AddContainerViewController.swift */; };
-		5126EE97226CB48A00C22AFC /* NavigationStateController.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5126EE96226CB48A00C22AFC /* NavigationStateController.swift */; };
+		5126EE97226CB48A00C22AFC /* AppCoordinator.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5126EE96226CB48A00C22AFC /* AppCoordinator.swift */; };
 		5127B238222B4849006D641D /* DetailKeyboardDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 5127B236222B4849006D641D /* DetailKeyboardDelegate.swift */; };
 		5127B23A222B4849006D641D /* DetailKeyboardShortcuts.plist in Resources */ = {isa = PBXBuildFile; fileRef = 5127B237222B4849006D641D /* DetailKeyboardShortcuts.plist */; };
 		512E08E62268800D00BDCFDD /* FolderTreeControllerDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 849A97A11ED9F180007D329B /* FolderTreeControllerDelegate.swift */; };
@@ -666,7 +666,7 @@
 		51121AA12265430A00BC0EC1 /* NetNewsWire_iOS_target.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; path = NetNewsWire_iOS_target.xcconfig; sourceTree = "<group>"; };
 		51121B5A22661FEF00BC0EC1 /* AddContainerViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AddContainerViewController.swift; sourceTree = "<group>"; };
 		51126DA3225FDE2F00722696 /* RSImage-Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "RSImage-Extensions.swift"; sourceTree = "<group>"; };
-		5126EE96226CB48A00C22AFC /* NavigationStateController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NavigationStateController.swift; sourceTree = "<group>"; };
+		5126EE96226CB48A00C22AFC /* AppCoordinator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppCoordinator.swift; sourceTree = "<group>"; };
 		5127B236222B4849006D641D /* DetailKeyboardDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DetailKeyboardDelegate.swift; sourceTree = "<group>"; };
 		5127B237222B4849006D641D /* DetailKeyboardShortcuts.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = DetailKeyboardShortcuts.plist; sourceTree = "<group>"; };
 		512E08F722688F7C00BDCFDD /* MasterFeedTableViewSectionHeader.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MasterFeedTableViewSectionHeader.swift; sourceTree = "<group>"; };
@@ -1709,10 +1709,10 @@
 				84C9FC9F2262A1B300D921D6 /* Main.storyboard */,
 				840D617E2029031C009BC708 /* AppDelegate.swift */,
 				519E743422C663F900A78E47 /* SceneDelegate.swift */,
+				5126EE96226CB48A00C22AFC /* AppCoordinator.swift */,
 				51C45254226507D200C03939 /* AppAssets.swift */,
 				51C45255226507D200C03939 /* AppDefaults.swift */,
 				51E3EB3C229AB08300645299 /* ErrorHandler.swift */,
-				5126EE96226CB48A00C22AFC /* NavigationStateController.swift */,
 				51C4525D226508F600C03939 /* MasterFeed */,
 				51C4526D2265091600C03939 /* MasterTimeline */,
 				51C4527D2265092C00C03939 /* Detail */,
@@ -2346,7 +2346,7 @@
 				51C452792265091600C03939 /* MasterTimelineTableViewCell.swift in Sources */,
 				51C452852265093600C03939 /* AddFeedFolderPickerData.swift in Sources */,
 				51C4526B226508F600C03939 /* MasterFeedViewController.swift in Sources */,
-				5126EE97226CB48A00C22AFC /* NavigationStateController.swift in Sources */,
+				5126EE97226CB48A00C22AFC /* AppCoordinator.swift in Sources */,
 				51EF0F77227716200050506E /* FaviconGenerator.swift in Sources */,
 				51C4525A226508D600C03939 /* UIStoryboard-Extensions.swift in Sources */,
 				5183CCEF227125970010922C /* SettingsViewController.swift in Sources */,

iOS/AppCoordinator.swift

@@ -0,0 +1,663 @@
+//
+//  NavigationModelController.swift
+//  NetNewsWire-iOS
+//
+//  Created by Maurice Parker on 4/21/19.
+//  Copyright © 2019 Ranchero Software. All rights reserved.
+//
+
+import Foundation
+import Account
+import Articles
+import RSCore
+import RSTree
+
+public extension Notification.Name {
+	static let MasterSelectionDidChange = Notification.Name(rawValue: "MasterSelectionDidChange")
+	static let BackingStoresDidRebuild = Notification.Name(rawValue: "BackingStoresDidRebuild")
+	static let ArticlesReinitialized = Notification.Name(rawValue: "ArticlesReinitialized")
+	static let ArticleDataDidChange = Notification.Name(rawValue: "ArticleDataDidChange")
+	static let ArticlesDidChange = Notification.Name(rawValue: "ArticlesDidChange")
+	static let ArticleSelectionDidChange = Notification.Name(rawValue: "ArticleSelectionDidChange")
+}
+
+class AppCoordinator {
+
+	static let fetchAndMergeArticlesQueue = CoalescingQueue(name: "Fetch and Merge Articles", interval: 0.5)
+	
+	private var articleRowMap = [String: Int]() // articleID: rowIndex
+	
+	private var animatingChanges = false
+	private var expandedNodes = [Node]()
+	private var shadowTable = [[Node]]()
+	
+	private var sortDirection = AppDefaults.timelineSortDirection {
+		didSet {
+			if sortDirection != oldValue {
+				sortDirectionDidChange()
+			}
+		}
+	}
+
+	private let treeControllerDelegate = FeedTreeControllerDelegate()
+	lazy var treeController: TreeController = {
+		return TreeController(delegate: treeControllerDelegate)
+	}()
+	
+	var rootNode: Node {
+		return treeController.rootNode
+	}
+	
+	var numberOfSections: Int {
+		return shadowTable.count
+	}
+
+	var currentMasterIndexPath: IndexPath? {
+		didSet {
+			guard let ip = currentMasterIndexPath, let node = nodeFor(ip) else {
+				assertionFailure()
+				return
+			}
+			if let fetcher = node.representedObject as? ArticleFetcher {
+				timelineFetcher = fetcher
+			}
+			NotificationCenter.default.post(name: .MasterSelectionDidChange, object: self, userInfo: nil)
+		}
+	}
+	
+	var timelineName: String? {
+		return (timelineFetcher as? DisplayNameProvider)?.nameForDisplay
+	}
+	
+	var timelineFetcher: ArticleFetcher? {
+		didSet {
+			currentArticleIndexPath = nil
+			if timelineFetcher is Feed {
+				showFeedNames = false
+			} else {
+				showFeedNames = true
+			}
+			fetchArticles()
+			NotificationCenter.default.post(name: .ArticlesReinitialized, object: self, userInfo: nil)
+		}
+	}
+	
+	
+	var showFeedNames = false
+	var showAvatars = false
+
+	var isPrevArticleAvailable: Bool {
+		guard let indexPath = currentArticleIndexPath else {
+			return false
+		}
+		return indexPath.row > 0
+	}
+	
+	var isNextArticleAvailable: Bool {
+		guard let indexPath = currentArticleIndexPath else {
+			return false
+		}
+		return indexPath.row + 1 < articles.count
+	}
+	
+	var prevArticleIndexPath: IndexPath? {
+		guard let indexPath = currentArticleIndexPath else {
+			return nil
+		}
+		return IndexPath(row: indexPath.row - 1, section: indexPath.section)
+	}
+	
+	var nextArticleIndexPath: IndexPath? {
+		guard let indexPath = currentArticleIndexPath else {
+			return nil
+		}
+		return IndexPath(row: indexPath.row + 1, section: indexPath.section)
+	}
+	
+	var firstUnreadArticleIndexPath: IndexPath? {
+		for (row, article) in articles.enumerated() {
+			if !article.status.read {
+				return IndexPath(row: row, section: 0)
+			}
+		}
+		return nil
+	}
+	
+	var currentArticle: Article? {
+		if let indexPath = currentArticleIndexPath {
+			return articles[indexPath.row]
+		}
+		return nil
+	}
+	
+	var currentArticleIndexPath: IndexPath? {
+		didSet {
+			if currentArticleIndexPath != oldValue {
+				NotificationCenter.default.post(name: .ArticleSelectionDidChange, object: self, userInfo: nil)
+			}
+		}
+	}
+	
+	var articles = ArticleArray() {
+		didSet {
+			if articles == oldValue {
+				return
+			}
+			if articles.representSameArticlesInSameOrder(as: oldValue) {
+				articleRowMap = [String: Int]()
+				NotificationCenter.default.post(name: .ArticleDataDidChange, object: self, userInfo: nil)
+				return
+			}
+			updateShowAvatars()
+			articleRowMap = [String: Int]()
+			NotificationCenter.default.post(name: .ArticlesDidChange, object: self, userInfo: nil)
+		}
+	}
+	
+	var isTimelineUnreadAvailable: Bool {
+		if let unreadProvider = timelineFetcher as? UnreadCountProvider {
+			return unreadProvider.unreadCount > 0
+		}
+		return false
+	}
+	
+	var isAnyUnreadAvailable: Bool {
+		return appDelegate.unreadCount > 0
+	}
+	
+	init() {
+
+		for section in treeController.rootNode.childNodes {
+			expandedNodes.append(section)
+			shadowTable.append([Node]())
+		}
+		
+		rebuildShadowTable()
+		
+		NotificationCenter.default.addObserver(self, selector: #selector(containerChildrenDidChange(_:)), name: .ChildrenDidChange, object: nil)
+		NotificationCenter.default.addObserver(self, selector: #selector(batchUpdateDidPerform(_:)), name: .BatchUpdateDidPerform, object: nil)
+		NotificationCenter.default.addObserver(self, selector: #selector(displayNameDidChange(_:)), name: .DisplayNameDidChange, object: nil)
+		NotificationCenter.default.addObserver(self, selector: #selector(accountStateDidChange(_:)), name: .AccountStateDidChange, object: nil)
+		NotificationCenter.default.addObserver(self, selector: #selector(accountsDidChange(_:)), name: .AccountsDidChange, object: nil)
+		
+		NotificationCenter.default.addObserver(self, selector: #selector(userDefaultsDidChange(_:)), name: UserDefaults.didChangeNotification, object: nil)
+		NotificationCenter.default.addObserver(self, selector: #selector(accountDidDownloadArticles(_:)), name: .AccountDidDownloadArticles, object: nil)
+		
+	}
+	
+	// MARK: Notifications
+	
+	@objc func containerChildrenDidChange(_ note: Notification) {
+		rebuildBackingStores()
+	}
+	
+	@objc func batchUpdateDidPerform(_ notification: Notification) {
+		rebuildBackingStores()
+	}
+	
+	@objc func displayNameDidChange(_ note: Notification) {
+		rebuildBackingStores()
+	}
+
+	@objc func accountStateDidChange(_ note: Notification) {
+		rebuildBackingStores()
+	}
+	
+	@objc func accountsDidChange(_ note: Notification) {
+		rebuildBackingStores()
+	}
+
+	@objc func userDefaultsDidChange(_ note: Notification) {
+		self.sortDirection = AppDefaults.timelineSortDirection
+	}
+	
+	@objc func accountDidDownloadArticles(_ note: Notification) {
+		
+		guard let feeds = note.userInfo?[Account.UserInfoKey.feeds] as? Set<Feed> else {
+			return
+		}
+		
+		let shouldFetchAndMergeArticles = timelineFetcherContainsAnyFeed(feeds) || timelineFetcherContainsAnyPseudoFeed()
+		if shouldFetchAndMergeArticles {
+			queueFetchAndMergeArticles()
+		}
+		
+	}
+
+	// MARK: API
+	
+	func beginUpdates() {
+		animatingChanges = true
+	}
+
+	func endUpdates() {
+		animatingChanges = false
+	}
+	
+	func rowsInSection(_ section: Int) -> Int {
+		return shadowTable[section].count
+	}
+	
+	func rebuildShadowTable() {
+		
+		shadowTable = [[Node]]()
+
+		for i in 0..<treeController.rootNode.numberOfChildNodes {
+			
+			var result = [Node]()
+			
+			if let nodes = treeController.rootNode.childAtIndex(i)?.childNodes {
+				for node in nodes {
+					result.append(node)
+					if expandedNodes.contains(node) {
+						for child in node.childNodes {
+							result.append(child)
+						}
+					}
+				}
+			}
+			
+			shadowTable.append(result)
+			
+		}
+		
+	}
+
+	func isExpanded(_ node: Node) -> Bool {
+		return expandedNodes.contains(node)
+	}
+	
+	func nodeFor(_ indexPath: IndexPath) -> Node? {
+		guard indexPath.section < shadowTable.count || indexPath.row < shadowTable[indexPath.section].count else {
+			return nil
+		}
+		return shadowTable[indexPath.section][indexPath.row]
+	}
+	
+	func indexPathFor(_ node: Node) -> IndexPath? {
+		for i in 0..<shadowTable.count {
+			if let row = shadowTable[i].firstIndex(of: node) {
+				return IndexPath(row: row, section: i)
+			}
+		}
+		return nil
+	}
+	
+	func expand(section: Int, completion: ([IndexPath]) -> ()) {
+		
+		guard let expandNode = treeController.rootNode.childAtIndex(section) else {
+			return
+		}
+		expandedNodes.append(expandNode)
+		
+		animatingChanges = true
+		
+		var indexPathsToInsert = [IndexPath]()
+		var i = 0
+		
+		func addNode(_ node: Node) {
+			indexPathsToInsert.append(IndexPath(row: i, section: section))
+			shadowTable[section].insert(node, at: i)
+			i = i + 1
+		}
+		
+		for child in expandNode.childNodes {
+			addNode(child)
+			if expandedNodes.contains(child) {
+				for gChild in child.childNodes {
+					addNode(gChild)
+				}
+			}
+		}
+		
+		completion(indexPathsToInsert)
+		
+		animatingChanges = false
+		
+	}
+	
+	func expand(_ indexPath: IndexPath, completion: ([IndexPath]) -> ()) {
+		
+		let expandNode = shadowTable[indexPath.section][indexPath.row]
+		expandedNodes.append(expandNode)
+		
+		animatingChanges = true
+		
+		var indexPathsToInsert = [IndexPath]()
+		for i in 0..<expandNode.childNodes.count {
+			if let child = expandNode.childAtIndex(i) {
+				let nextIndex = indexPath.row + i + 1
+				indexPathsToInsert.append(IndexPath(row: nextIndex, section: indexPath.section))
+				shadowTable[indexPath.section].insert(child, at: nextIndex)
+			}
+		}
+		
+		completion(indexPathsToInsert)
+		
+		animatingChanges = false
+		
+	}
+	
+	func collapse(section: Int, completion: ([IndexPath]) -> ()) {
+		
+		animatingChanges = true
+		
+		guard let collapseNode = treeController.rootNode.childAtIndex(section) else {
+			return
+		}
+		
+		if let removeNode = expandedNodes.firstIndex(of: collapseNode) {
+			expandedNodes.remove(at: removeNode)
+		}
+		
+		var indexPathsToRemove = [IndexPath]()
+		for i in 0..<shadowTable[section].count {
+			indexPathsToRemove.append(IndexPath(row: i, section: section))
+		}
+		shadowTable[section] = [Node]()
+		
+		completion(indexPathsToRemove)
+		
+		animatingChanges = false
+		
+	}
+	
+	func collapse(_ indexPath: IndexPath, completion: ([IndexPath]) -> ()) {
+		
+		animatingChanges = true
+		
+		let collapseNode = shadowTable[indexPath.section][indexPath.row]
+		if let removeNode = expandedNodes.firstIndex(of: collapseNode) {
+			expandedNodes.remove(at: removeNode)
+		}
+		
+		var indexPathsToRemove = [IndexPath]()
+		
+		for child in collapseNode.childNodes {
+			if let index = shadowTable[indexPath.section].firstIndex(of: child) {
+				indexPathsToRemove.append(IndexPath(row: index, section: indexPath.section))
+			}
+		}
+		
+		for child in collapseNode.childNodes {
+			if let index = shadowTable[indexPath.section].firstIndex(of: child) {
+				shadowTable[indexPath.section].remove(at: index)
+			}
+		}
+		
+		completion(indexPathsToRemove)
+		
+		animatingChanges = false
+		
+	}
+	
+	func indexesForArticleIDs(_ articleIDs: Set<String>) -> IndexSet {
+		
+		var indexes = IndexSet()
+		
+		articleIDs.forEach { (articleID) in
+			guard let oneIndex = row(for: articleID) else {
+				return
+			}
+			if oneIndex != NSNotFound {
+				indexes.insert(oneIndex)
+			}
+		}
+		
+		return indexes
+	}
+	
+	func selectNextUnread() {
+		
+		// This should never happen, but I don't want to risk throwing us
+		// into an infinate loop searching for an unread that isn't there.
+		if appDelegate.unreadCount < 1 {
+			return
+		}
+		
+		if selectNextUnreadArticleInTimeline() {
+			return
+		}
+		
+		selectNextUnreadFeedFetcher()
+		selectNextUnreadArticleInTimeline()
+		
+	}
+	
+}
+
+// MARK: UISplitViewControllerDelegate
+
+extension AppCoordinator: UISplitViewControllerDelegate {
+
+	func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController:UIViewController, onto primaryViewController:UIViewController) -> Bool {
+		if currentArticle == nil {
+			// Return true to indicate that we have handled the collapse by doing nothing; the secondary controller will be discarded.
+			return true
+		}
+		return false
+	}
+
+}
+
+// MARK: Private
+
+private extension AppCoordinator {
+
+	func rebuildBackingStores() {
+		if !animatingChanges && !BatchUpdate.shared.isPerforming {
+			treeController.rebuild()
+			rebuildShadowTable()
+			NotificationCenter.default.post(name: .BackingStoresDidRebuild, object: self, userInfo: nil)
+		}
+	}
+	
+	func updateShowAvatars() {
+		
+		if showFeedNames {
+			self.showAvatars = true
+			return
+		}
+		
+		for article in articles {
+			if let authors = article.authors {
+				for author in authors {
+					if author.avatarURL != nil {
+						self.showAvatars = true
+						return
+					}
+				}
+			}
+		}
+		
+		self.showAvatars = false
+	}
+	
+	// MARK: Select Next Unread
+
+	@discardableResult
+	func selectNextUnreadArticleInTimeline() -> Bool {
+		
+		let startingRow: Int = {
+			if let indexPath = currentArticleIndexPath {
+				return indexPath.row
+			} else {
+				return 0
+			}
+		}()
+		
+		for i in startingRow..<articles.count {
+			let article = articles[i]
+			if !article.status.read {
+				currentArticleIndexPath = IndexPath(row: i, section: 0)
+				return true
+			}
+		}
+		
+		return false
+		
+	}
+	
+	func selectNextUnreadFeedFetcher() {
+		
+		guard let indexPath = currentMasterIndexPath else {
+			assertionFailure()
+			return
+		}
+		
+		// Increment or wrap around the IndexPath
+		let nextIndexPath: IndexPath = {
+			if indexPath.row + 1 >= shadowTable[indexPath.section].count {
+				if indexPath.section + 1 >= shadowTable.count {
+					return IndexPath(row: 0, section: 0)
+				} else {
+					return IndexPath(row: 0, section: indexPath.section + 1)
+				}
+			} else {
+				return IndexPath(row: indexPath.row + 1, section: indexPath.section)
+			}
+		}()
+		
+		if selectNextUnreadFeedFetcher(startingWith: nextIndexPath) {
+			return
+		}
+		selectNextUnreadFeedFetcher(startingWith: IndexPath(row: 0, section: 0))
+		
+	}
+	
+	@discardableResult
+	func selectNextUnreadFeedFetcher(startingWith indexPath: IndexPath) -> Bool {
+		
+		for i in indexPath.section..<shadowTable.count {
+			
+			for j in indexPath.row..<shadowTable[indexPath.section].count {
+				
+				let nextIndexPath = IndexPath(row: j, section: i)
+				guard let node = nodeFor(nextIndexPath), let unreadCountProvider = node.representedObject as? UnreadCountProvider else {
+					assertionFailure()
+					return true
+				}
+				
+				if expandedNodes.contains(node) {
+					continue
+				}
+				
+				if unreadCountProvider.unreadCount > 0 {
+					currentMasterIndexPath = nextIndexPath
+					return true
+				}
+				
+			}
+			
+		}
+		
+		return false
+		
+	}
+	
+	// MARK: Fetching Articles
+	
+	func fetchArticles() {
+		
+		guard let timelineFetcher = timelineFetcher else {
+			articles = ArticleArray()
+			return
+		}
+		
+		let fetchedArticles = timelineFetcher.fetchArticles()
+		updateArticles(with: fetchedArticles)
+		
+	}
+	
+	func emptyTheTimeline() {
+		if !articles.isEmpty {
+			articles = [Article]()
+		}
+	}
+	
+	func sortDirectionDidChange() {
+		updateArticles(with: Set(articles))
+	}
+	
+	func updateArticles(with unsortedArticles: Set<Article>) {
+		let sortedArticles = Array(unsortedArticles).sortedByDate(sortDirection)
+		if articles != sortedArticles {
+			articles = sortedArticles
+		}
+	}
+	
+	func row(for articleID: String) -> Int? {
+		updateArticleRowMapIfNeeded()
+		return articleRowMap[articleID]
+	}
+	
+	func updateArticleRowMap() {
+		var rowMap = [String: Int]()
+		var index = 0
+		articles.forEach { (article) in
+			rowMap[article.articleID] = index
+			index += 1
+		}
+		articleRowMap = rowMap
+	}
+	
+	func updateArticleRowMapIfNeeded() {
+		if articleRowMap.isEmpty {
+			updateArticleRowMap()
+		}
+	}
+	
+	func queueFetchAndMergeArticles() {
+		AppCoordinator.fetchAndMergeArticlesQueue.add(self, #selector(fetchAndMergeArticles))
+	}
+	
+	@objc func fetchAndMergeArticles() {
+		
+		guard let timelineFetcher = timelineFetcher else {
+			return
+		}
+		
+		var unsortedArticles = timelineFetcher.fetchArticles()
+		
+		// Merge articles by articleID. For any unique articleID in current articles, add to unsortedArticles.
+		let unsortedArticleIDs = unsortedArticles.articleIDs()
+		for article in articles {
+			if !unsortedArticleIDs.contains(article.articleID) {
+				unsortedArticles.insert(article)
+			}
+		}
+		
+		updateArticles(with: unsortedArticles)
+		
+	}
+	
+	func timelineFetcherContainsAnyPseudoFeed() -> Bool {
+		if timelineFetcher is PseudoFeed {
+			return true
+		}
+		return false
+	}
+	
+	func timelineFetcherContainsAnyFeed(_ feeds: Set<Feed>) -> Bool {
+		
+		// Return true if there’s a match or if a folder contains (recursively) one of feeds
+		
+		if let feed = timelineFetcher as? Feed {
+			for oneFeed in feeds {
+				if feed.feedID == oneFeed.feedID || feed.url == oneFeed.url {
+					return true
+				}
+			}
+		} else if let folder = timelineFetcher as? Folder {
+			for oneFeed in feeds {
+				if folder.hasFeed(with: oneFeed.feedID) || folder.hasFeed(withURL: oneFeed.url) {
+					return true
+				}
+			}
+		}
+		
+		return false
+		
+	}
+	
+}

iOS/Detail/DetailViewController.swift

@@ -23,7 +23,7 @@ class DetailViewController: UIViewController {
 	@IBOutlet weak var browserBarButtonItem: UIBarButtonItem!
 	@IBOutlet weak var webView: WKWebView!
 	
-	weak var navState: NavigationStateController?
+	weak var coordinator: AppCoordinator?
 	
 	override func viewDidLoad() {
 		
@@ -36,7 +36,7 @@ class DetailViewController: UIViewController {
 		
 		NotificationCenter.default.addObserver(self, selector: #selector(unreadCountDidChange(_:)), name: .UnreadCountDidChange, object: nil)
 		NotificationCenter.default.addObserver(self, selector: #selector(statusesDidChange(_:)), name: .StatusesDidChange, object: nil)
-		NotificationCenter.default.addObserver(self, selector: #selector(articleSelectionDidChange(_:)), name: .ArticleSelectionDidChange, object: navState)
+		NotificationCenter.default.addObserver(self, selector: #selector(articleSelectionDidChange(_:)), name: .ArticleSelectionDidChange, object: coordinator)
 		NotificationCenter.default.addObserver(self, selector: #selector(progressDidChange(_:)), name: .AccountRefreshProgressDidChange, object: nil)
 		NotificationCenter.default.addObserver(self, selector: #selector(contentSizeCategoryDidChange(_:)), name: UIContentSizeCategory.didChangeNotification, object: nil)
 	}
@@ -47,14 +47,14 @@ class DetailViewController: UIViewController {
 	}
 	
 	func markAsRead() {
-		if let article = navState?.currentArticle {
+		if let article = coordinator?.currentArticle {
 			markArticles(Set([article]), statusKey: .read, flag: true)
 		}
 	}
 	
 	func updateUI() {
 		
-		guard let article = navState?.currentArticle else {
+		guard let article = coordinator?.currentArticle else {
 			nextUnreadBarButtonItem.isEnabled = false
 			prevArticleBarButtonItem.isEnabled = false
 			nextArticleBarButtonItem.isEnabled = false
@@ -65,9 +65,9 @@ class DetailViewController: UIViewController {
 			return
 		}
 		
-		nextUnreadBarButtonItem.isEnabled = navState?.isAnyUnreadAvailable ?? false
-		prevArticleBarButtonItem.isEnabled = navState?.isPrevArticleAvailable ?? false
-		nextArticleBarButtonItem.isEnabled = navState?.isNextArticleAvailable ?? false
+		nextUnreadBarButtonItem.isEnabled = coordinator?.isAnyUnreadAvailable ?? false
+		prevArticleBarButtonItem.isEnabled = coordinator?.isPrevArticleAvailable ?? false
+		nextArticleBarButtonItem.isEnabled = coordinator?.isNextArticleAvailable ?? false
 
 		readBarButtonItem.isEnabled = true
 		starBarButtonItem.isEnabled = true
@@ -80,7 +80,7 @@ class DetailViewController: UIViewController {
 		let starImage = article.status.starred ? AppAssets.starClosedImage : AppAssets.starOpenImage
 		starBarButtonItem.image = starImage
 		
-		if let timelineName = navState?.timelineName {
+		if let timelineName = coordinator?.timelineName {
 			if navigationController?.navigationItem.backBarButtonItem?.title != timelineName {
 				let backItem = UIBarButtonItem(title: timelineName, style: .plain, target: nil, action: nil)
 				navigationController?.navigationItem.backBarButtonItem = backItem
@@ -91,7 +91,7 @@ class DetailViewController: UIViewController {
 	
 	func reloadHTML() {
 		
-		guard let article = navState?.currentArticle, let webView = webView else {
+		guard let article = coordinator?.currentArticle, let webView = webView else {
 			return
 		}
 		let style = ArticleStylesManager.shared.currentStyle
@@ -110,7 +110,7 @@ class DetailViewController: UIViewController {
 		guard let articles = note.userInfo?[Account.UserInfoKey.articles] as? Set<Article> else {
 			return
 		}
-		if articles.count == 1 && articles.first?.articleID == navState?.currentArticle?.articleID {
+		if articles.count == 1 && articles.first?.articleID == coordinator?.currentArticle?.articleID {
 			updateUI()
 		}
 	}
@@ -132,41 +132,41 @@ class DetailViewController: UIViewController {
 	// MARK: Actions
 	
 	@IBAction func nextUnread(_ sender: Any) {
-		navState?.selectNextUnread()
+		coordinator?.selectNextUnread()
 	}
 	
 	@IBAction func prevArticle(_ sender: Any) {
-		navState?.currentArticleIndexPath = navState?.prevArticleIndexPath
+		coordinator?.currentArticleIndexPath = coordinator?.prevArticleIndexPath
 	}
 	
 	@IBAction func nextArticle(_ sender: Any) {
-		navState?.currentArticleIndexPath = navState?.nextArticleIndexPath
+		coordinator?.currentArticleIndexPath = coordinator?.nextArticleIndexPath
 	}
 	
 	@IBAction func toggleRead(_ sender: Any) {
-		if let article = navState?.currentArticle {
+		if let article = coordinator?.currentArticle {
 			markArticles(Set([article]), statusKey: .read, flag: !article.status.read)
 		}
 	}
 	
 	@IBAction func toggleStar(_ sender: Any) {
-		if let article = navState?.currentArticle {
+		if let article = coordinator?.currentArticle {
 			markArticles(Set([article]), statusKey: .starred, flag: !article.status.starred)
 		}
 	}
 	
 	@IBAction func openBrowser(_ sender: Any) {
-		guard let preferredLink = navState?.currentArticle?.preferredLink, let url = URL(string: preferredLink) else {
+		guard let preferredLink = coordinator?.currentArticle?.preferredLink, let url = URL(string: preferredLink) else {
 			return
 		}
 		UIApplication.shared.open(url, options: [:])
 	}
 	
 	@IBAction func showActivityDialog(_ sender: Any) {
-		guard let preferredLink = navState?.currentArticle?.preferredLink, let url = URL(string: preferredLink) else {
+		guard let preferredLink = coordinator?.currentArticle?.preferredLink, let url = URL(string: preferredLink) else {
 			return
 		}
-		let itemSource = ArticleActivityItemSource(url: url, subject: navState?.currentArticle?.title)
+		let itemSource = ArticleActivityItemSource(url: url, subject: coordinator?.currentArticle?.title)
 		let activityViewController = UIActivityViewController(activityItems: [itemSource], applicationActivities: nil)
 		activityViewController.popoverPresentationController?.barButtonItem = self.actionBarButtonItem
 		

iOS/MasterFeed/MasterFeedViewController.swift

@@ -20,7 +20,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	
 	var undoableCommands = [UndoableCommand]()
 	
-	let navState = NavigationStateController()
+	weak var coordinator: AppCoordinator!
 	override var canBecomeFirstResponder: Bool {
 		return true
 	}
@@ -40,8 +40,8 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 		NotificationCenter.default.addObserver(self, selector: #selector(accountsDidChange(_:)), name: .AccountsDidChange, object: nil)
 		NotificationCenter.default.addObserver(self, selector: #selector(accountStateDidChange(_:)), name: .AccountStateDidChange, object: nil)
 		
-		NotificationCenter.default.addObserver(self, selector: #selector(backingStoresDidRebuild(_:)), name: .BackingStoresDidRebuild, object: navState)
-		NotificationCenter.default.addObserver(self, selector: #selector(masterSelectionDidChange(_:)), name: .MasterSelectionDidChange, object: navState)
+		NotificationCenter.default.addObserver(self, selector: #selector(backingStoresDidRebuild(_:)), name: .BackingStoresDidRebuild, object: coordinator)
+		NotificationCenter.default.addObserver(self, selector: #selector(masterSelectionDidChange(_:)), name: .MasterSelectionDidChange, object: coordinator)
 		NotificationCenter.default.addObserver(self, selector: #selector(contentSizeCategoryDidChange), name: UIContentSizeCategory.didChangeNotification, object: nil)
 
 		refreshControl = UIRefreshControl()
@@ -82,8 +82,8 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 		}
 		
 		if let account = representedObject as? Account {
-			if let node = navState.rootNode.childNodeRepresentingObject(account) {
-				let sectionIndex = navState.rootNode.indexOfChild(node)!
+			if let node = coordinator.rootNode.childNodeRepresentingObject(account) {
+				let sectionIndex = coordinator.rootNode.indexOfChild(node)!
 				if let headerView = tableView.headerView(forSection: sectionIndex) as? MasterFeedTableViewSectionHeader {
 					headerView.unreadCount = account.unreadCount
 				}
@@ -91,8 +91,8 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 			return
 		}
 		
-		guard let node = navState.rootNode.descendantNodeRepresentingObject(representedObject as AnyObject),
-			let indexPath = navState.indexPathFor(node) else {
+		guard let node = coordinator.rootNode.descendantNodeRepresentingObject(representedObject as AnyObject),
+			let indexPath = coordinator.indexPathFor(node) else {
 				return
 		}
 
@@ -119,27 +119,27 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	@objc func userDidAddFeed(_ notification: Notification) {
 		
 		guard let feed = notification.userInfo?[UserInfoKey.feed],
-			let node = navState.rootNode.descendantNodeRepresentingObject(feed as AnyObject) else {
+			let node = coordinator.rootNode.descendantNodeRepresentingObject(feed as AnyObject) else {
 				return
 		}
 		
-		if let indexPath = navState.indexPathFor(node) {
+		if let indexPath = coordinator.indexPathFor(node) {
 			tableView.scrollToRow(at: indexPath, at: .middle, animated: true)
 			return
 		}
 	
 		// It wasn't already visable, so expand its folder and try again
-		guard let parent = node.parent, let indexPath = navState.indexPathFor(parent) else {
+		guard let parent = node.parent, let indexPath = coordinator.indexPathFor(parent) else {
 			return
 		}
 		
-		navState.expand(indexPath) { [weak self] indexPaths in
+		coordinator.expand(indexPath) { [weak self] indexPaths in
 			self?.tableView.beginUpdates()
 			self?.tableView.insertRows(at: indexPaths, with: .automatic)
 			self?.tableView.endUpdates()
 		}
 
-		if let indexPath = navState.indexPathFor(node) {
+		if let indexPath = coordinator.indexPathFor(node) {
 			tableView.scrollToRow(at: indexPath, at: .middle, animated: true)
 		}
 
@@ -154,7 +154,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	}
 	
 	@objc func masterSelectionDidChange(_ note: Notification) {
-		if let indexPath = navState.currentMasterIndexPath {
+		if let indexPath = coordinator.currentMasterIndexPath {
 			if tableView.indexPathForSelectedRow != indexPath {
 				tableView.selectRow(at: indexPath, animated: true, scrollPosition: .middle)
 			}
@@ -168,16 +168,16 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	// MARK: Table View
 	
 	override func numberOfSections(in tableView: UITableView) -> Int {
-		return navState.numberOfSections
+		return coordinator.numberOfSections
 	}
 	
 	override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
-		return navState.rowsInSection(section)
+		return coordinator.rowsInSection(section)
 	}
 	
 	override func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
 
-		guard let nameProvider = navState.rootNode.childAtIndex(section)?.representedObject as? DisplayNameProvider else {
+		guard let nameProvider = coordinator.rootNode.childAtIndex(section)?.representedObject as? DisplayNameProvider else {
 			return 44
 		}
 		
@@ -191,14 +191,14 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	
 	override func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? {
 		
-		guard let nameProvider = navState.rootNode.childAtIndex(section)?.representedObject as? DisplayNameProvider else {
+		guard let nameProvider = coordinator.rootNode.childAtIndex(section)?.representedObject as? DisplayNameProvider else {
 			return nil
 		}
 		
 		let headerView = tableView.dequeueReusableHeaderFooterView(withIdentifier: "SectionHeader") as! MasterFeedTableViewSectionHeader
 		headerView.name = nameProvider.nameForDisplay
 		
-		guard let sectionNode = navState.rootNode.childAtIndex(section) else {
+		guard let sectionNode = coordinator.rootNode.childAtIndex(section) else {
 			return headerView
 		}
 		
@@ -209,7 +209,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 		}
 		
 		headerView.tag = section
-		headerView.disclosureExpanded = navState.isExpanded(sectionNode)
+		headerView.disclosureExpanded = coordinator.isExpanded(sectionNode)
 
 		let tap = UITapGestureRecognizer(target: self, action:#selector(self.toggleSectionHeader(_:)))
 		headerView.addGestureRecognizer(tap)
@@ -230,7 +230,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 		
 		let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! MasterFeedTableViewCell
 		
-		guard let node = navState.nodeFor(indexPath) else {
+		guard let node = coordinator.nodeFor(indexPath) else {
 			return cell
 		}
 		
@@ -240,7 +240,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	}
 	
 	override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
-		guard let node = navState.nodeFor(indexPath), !(node.representedObject is PseudoFeed) else {
+		guard let node = coordinator.nodeFor(indexPath), !(node.representedObject is PseudoFeed) else {
 			return false
 		}
 		return true
@@ -273,14 +273,14 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
 		
 		let timeline = UIStoryboard.main.instantiateController(ofType: MasterTimelineViewController.self)
-		timeline.navState = navState
-		navState.currentMasterIndexPath = indexPath
+		timeline.coordinator = coordinator
+		coordinator.currentMasterIndexPath = indexPath
 		self.navigationController?.pushViewController(timeline, animated: true)
 
 	}
 
 	override func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool {
-		guard let node = navState.nodeFor(indexPath) else {
+		guard let node = coordinator.nodeFor(indexPath) else {
 			return false
 		}
 		return node.representedObject is Feed
@@ -296,13 +296,13 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 			return proposedDestinationIndexPath
 		}()
 		
-		guard let draggedNode = navState.nodeFor(sourceIndexPath), let destNode = navState.nodeFor(destIndexPath), let parentNode = destNode.parent else {
+		guard let draggedNode = coordinator.nodeFor(sourceIndexPath), let destNode = coordinator.nodeFor(destIndexPath), let parentNode = destNode.parent else {
 			assertionFailure("This should never happen")
 			return sourceIndexPath
 		}
 		
 		// If this is a folder and isn't expanded or doesn't have any entries, let the users drop on it
-		if destNode.representedObject is Folder && (destNode.numberOfChildNodes == 0 || !navState.isExpanded(destNode)) {
+		if destNode.representedObject is Folder && (destNode.numberOfChildNodes == 0 || !coordinator.isExpanded(destNode)) {
 			let movementAdjustment = sourceIndexPath > destIndexPath ? 1 : 0
 			return IndexPath(row: destIndexPath.row + movementAdjustment, section: destIndexPath.section)
 		}
@@ -323,7 +323,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 			if parentNode.representedObject is Account {
 				return IndexPath(row: 0, section: destIndexPath.section)
 			} else {
-				return navState.indexPathFor(parentNode)!
+				return coordinator.indexPathFor(parentNode)!
 			}
 			
 		} else {
@@ -333,10 +333,10 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 			let movementAdjustment = sourceIndexPath < destIndexPath ? 1 : 0
 			let adjustedIndex = index - movementAdjustment
 			if adjustedIndex >= sortedNodes.count {
-				let lastSortedIndexPath = navState.indexPathFor(sortedNodes[sortedNodes.count - 1])!
+				let lastSortedIndexPath = coordinator.indexPathFor(sortedNodes[sortedNodes.count - 1])!
 				return IndexPath(row: lastSortedIndexPath.row + 1, section: lastSortedIndexPath.section)
 			} else {
-				return navState.indexPathFor(sortedNodes[adjustedIndex])!
+				return coordinator.indexPathFor(sortedNodes[adjustedIndex])!
 			}
 			
 		}
@@ -345,18 +345,18 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	
 	override func tableView(_ tableView: UITableView, moveRowAt sourceIndexPath: IndexPath, to destinationIndexPath: IndexPath) {
 
-		guard let sourceNode = navState.nodeFor(sourceIndexPath), let feed = sourceNode.representedObject as? Feed else {
+		guard let sourceNode = coordinator.nodeFor(sourceIndexPath), let feed = sourceNode.representedObject as? Feed else {
 			return
 		}
 
 		// Based on the drop we have to determine a node to start looking for a parent container.
 		let destNode: Node = {
 			if destinationIndexPath.row == 0 {
-				return navState.rootNode.childAtIndex(destinationIndexPath.section)!
+				return coordinator.rootNode.childAtIndex(destinationIndexPath.section)!
 			} else {
 				let movementAdjustment = sourceIndexPath > destinationIndexPath ? 1 : 0
 				let adjustedDestIndexPath = IndexPath(row: destinationIndexPath.row - movementAdjustment, section: destinationIndexPath.section)
-				return navState.nodeFor(adjustedDestIndexPath)!
+				return coordinator.nodeFor(adjustedDestIndexPath)!
 			}
 		}()
 
@@ -453,22 +453,22 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	@objc func toggleSectionHeader(_ sender: UITapGestureRecognizer) {
 		
 		guard let sectionIndex = sender.view?.tag,
-			let sectionNode = navState.rootNode.childAtIndex(sectionIndex),
+			let sectionNode = coordinator.rootNode.childAtIndex(sectionIndex),
 			let headerView = sender.view as? MasterFeedTableViewSectionHeader
 				else {
 					return
 		}
 		
-		if navState.isExpanded(sectionNode) {
+		if coordinator.isExpanded(sectionNode) {
 			headerView.disclosureExpanded = false
-			navState.collapse(section: sectionIndex) { [weak self] indexPaths in
+			coordinator.collapse(section: sectionIndex) { [weak self] indexPaths in
 				self?.tableView.beginUpdates()
 				self?.tableView.deleteRows(at: indexPaths, with: .automatic)
 				self?.tableView.endUpdates()
 			}
 		} else {
 			headerView.disclosureExpanded = true
-			navState.expand(section: sectionIndex) { [weak self] indexPaths in
+			coordinator.expand(section: sectionIndex) { [weak self] indexPaths in
 				self?.tableView.beginUpdates()
 				self?.tableView.insertRows(at: indexPaths, with: .automatic)
 				self?.tableView.endUpdates()
@@ -487,7 +487,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 		} else {
 			cell.indentationLevel = 0
 		}
-		cell.disclosureExpanded = navState.isExpanded(node)
+		cell.disclosureExpanded = coordinator.isExpanded(node)
 		cell.allowDisclosureSelection = node.canHaveChildNodes
 		
 		cell.name = nameFor(node)
@@ -525,14 +525,14 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 	func delete(indexPath: IndexPath) {
 
 		guard let undoManager = undoManager,
-			let deleteNode = navState.nodeFor(indexPath),
-			let deleteCommand = DeleteCommand(nodesToDelete: [deleteNode], treeController: navState.treeController, undoManager: undoManager, errorHandler: ErrorHandler.present(self))
+			let deleteNode = coordinator.nodeFor(indexPath),
+			let deleteCommand = DeleteCommand(nodesToDelete: [deleteNode], treeController: coordinator.treeController, undoManager: undoManager, errorHandler: ErrorHandler.present(self))
 				else {
 					return
 		}
 
 		var deleteIndexPaths = [indexPath]
-		if navState.isExpanded(deleteNode) {
+		if coordinator.isExpanded(deleteNode) {
 			for i in 0..<deleteNode.numberOfChildNodes {
 				deleteIndexPaths.append(IndexPath(row: indexPath.row + 1 + i, section: indexPath.section))
 			}
@@ -540,19 +540,19 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 		
 		pushUndoableCommand(deleteCommand)
 
-		navState.beginUpdates()
+		coordinator.beginUpdates()
 		deleteCommand.perform {
-			self.navState.treeController.rebuild()
-			self.navState.rebuildShadowTable()
+			self.coordinator.treeController.rebuild()
+			self.coordinator.rebuildShadowTable()
 			self.tableView.deleteRows(at: deleteIndexPaths, with: .automatic)
-			self.navState.endUpdates()
+			self.coordinator.endUpdates()
 		}
 		
 	}
 	
 	func rename(indexPath: IndexPath) {
 		
-		let name = (navState.nodeFor(indexPath)?.representedObject as? DisplayNameProvider)?.nameForDisplay ?? ""
+		let name = (coordinator.nodeFor(indexPath)?.representedObject as? DisplayNameProvider)?.nameForDisplay ?? ""
 		let formatString = NSLocalizedString("Rename “%@”", comment: "Feed finder")
 		let title = NSString.localizedStringWithFormat(formatString as NSString, name) as String
 		
@@ -564,7 +564,7 @@ class MasterFeedViewController: ProgressTableViewController, UndoableCommandRunn
 		let renameTitle = NSLocalizedString("Rename", comment: "Rename")
 		let renameAction = UIAlertAction(title: renameTitle, style: .default) { [weak self] action in
 			
-			guard let node = self?.navState.nodeFor(indexPath),
+			guard let node = self?.coordinator.nodeFor(indexPath),
 				let name = alertController.textFields?[0].text,
 				!name.isEmpty else {
 					return
@@ -630,7 +630,7 @@ private extension MasterFeedViewController {
 	}
 	
 	func updateUI() {
-		markAllAsReadButton.isEnabled = navState.isAnyUnreadAvailable
+		markAllAsReadButton.isEnabled = coordinator.isAnyUnreadAvailable
 		addNewItemButton.isEnabled = !AccountManager.shared.activeAccounts.isEmpty
 	}
 
@@ -649,7 +649,7 @@ private extension MasterFeedViewController {
 	
 	func applyToAvailableCells(_ callback: (MasterFeedTableViewCell, Node) -> Void) {
 		tableView.visibleCells.forEach { cell in
-			guard let indexPath = tableView.indexPath(for: cell), let node = navState.nodeFor(indexPath) else {
+			guard let indexPath = tableView.indexPath(for: cell), let node = coordinator.nodeFor(indexPath) else {
 				return
 			}
 			callback(cell as! MasterFeedTableViewCell, node)
@@ -673,7 +673,7 @@ private extension MasterFeedViewController {
 		guard let indexPath = tableView.indexPath(for: cell)  else {
 			return
 		}
-		navState.expand(indexPath) { [weak self] indexPaths in
+		coordinator.expand(indexPath) { [weak self] indexPaths in
 			self?.tableView.beginUpdates()
 			self?.tableView.insertRows(at: indexPaths, with: .automatic)
 			self?.tableView.endUpdates()
@@ -684,7 +684,7 @@ private extension MasterFeedViewController {
 		guard let indexPath = tableView.indexPath(for: cell) else {
 			return
 		}
-		navState.collapse(indexPath) { [weak self] indexPaths in
+		coordinator.collapse(indexPath) { [weak self] indexPaths in
 			self?.tableView.beginUpdates()
 			self?.tableView.deleteRows(at: indexPaths, with: .automatic)
 			self?.tableView.endUpdates()

iOS/MasterTimeline/MasterTimelineViewController.swift

@@ -18,7 +18,7 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 	@IBOutlet weak var markAllAsReadButton: UIBarButtonItem!
 	@IBOutlet weak var firstUnreadButton: UIBarButtonItem!
 	
-	weak var navState: NavigationStateController?
+	weak var coordinator: AppCoordinator!
 	var undoableCommands = [UndoableCommand]()
 	
 	override var canBecomeFirstResponder: Bool {
@@ -37,10 +37,10 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 		NotificationCenter.default.addObserver(self, selector: #selector(imageDidBecomeAvailable(_:)), name: .FaviconDidBecomeAvailable, object: nil)
 		NotificationCenter.default.addObserver(self, selector: #selector(userDefaultsDidChange(_:)), name: UserDefaults.didChangeNotification, object: nil)
 
-		NotificationCenter.default.addObserver(self, selector: #selector(articlesReinitialized(_:)), name: .ArticlesReinitialized, object: navState)
-		NotificationCenter.default.addObserver(self, selector: #selector(articleDataDidChange(_:)), name: .ArticleDataDidChange, object: navState)
-		NotificationCenter.default.addObserver(self, selector: #selector(articlesDidChange(_:)), name: .ArticlesDidChange, object: navState)
-		NotificationCenter.default.addObserver(self, selector: #selector(articleSelectionDidChange(_:)), name: .ArticleSelectionDidChange, object: navState)
+		NotificationCenter.default.addObserver(self, selector: #selector(articlesReinitialized(_:)), name: .ArticlesReinitialized, object: coordinator)
+		NotificationCenter.default.addObserver(self, selector: #selector(articleDataDidChange(_:)), name: .ArticleDataDidChange, object: coordinator)
+		NotificationCenter.default.addObserver(self, selector: #selector(articlesDidChange(_:)), name: .ArticlesDidChange, object: coordinator)
+		NotificationCenter.default.addObserver(self, selector: #selector(articleSelectionDidChange(_:)), name: .ArticleSelectionDidChange, object: coordinator)
 		NotificationCenter.default.addObserver(self, selector: #selector(contentSizeCategoryDidChange), name: UIContentSizeCategory.didChangeNotification, object: nil)
 
 		refreshControl = UIRefreshControl()
@@ -66,7 +66,7 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 	override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
 		if segue.identifier == "showDetail" {
 			let controller = (segue.destination as! UINavigationController).topViewController as! DetailViewController
-			controller.navState = navState
+			controller.coordinator = coordinator
 			controller.navigationItem.leftBarButtonItem = splitViewController?.displayModeButtonItem
 			controller.navigationItem.leftItemsSupplementBackButton = true
 			splitViewController?.toggleMasterView()
@@ -101,7 +101,7 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 		let markTitle = NSLocalizedString("Mark All Read", comment: "Mark All Read")
 		let markAction = UIAlertAction(title: markTitle, style: .default) { [weak self] (action) in
 
-			guard let articles = self?.navState?.articles,
+			guard let articles = self?.coordinator.articles,
 				let undoManager = self?.undoManager,
 				let markReadCommand = MarkStatusCommand(initialArticles: articles, markingRead: true, undoManager: undoManager) else {
 				return
@@ -119,7 +119,7 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 	}
 	
 	@IBAction func firstUnread(_ sender: Any) {
-		if let indexPath = navState?.firstUnreadArticleIndexPath {
+		if let indexPath = coordinator.firstUnreadArticleIndexPath {
 			tableView.scrollToRow(at: indexPath, at: .middle, animated: true)
 		}
 	}
@@ -131,14 +131,12 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
     }
 
     override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
-        return navState?.articles.count ?? 0
+        return coordinator.articles.count
     }
 
 	override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
 		
-		guard let article = navState?.articles[indexPath.row] else {
-			return nil
-		}
+		let article = coordinator.articles[indexPath.row]
 		
 		// Set up the read action
 		let readTitle = article.status.read ?
@@ -180,20 +178,14 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 	}
 
 	override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
-		
 		let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! MasterTimelineTableViewCell
-
-		guard let article = navState?.articles[indexPath.row] else {
-			return cell
-		}
-
+		let article = coordinator.articles[indexPath.row]
 		configureTimelineCell(cell, article: article)
-		
 		return cell
 	}
 	
 	override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
-		navState?.currentArticleIndexPath = indexPath
+		coordinator.currentArticleIndexPath = indexPath
 	}
 	
 	// MARK: Notifications
@@ -219,7 +211,7 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 		performBlockAndRestoreSelection {
 			tableView.indexPathsForVisibleRows?.forEach { indexPath in
 				
-				guard let article = navState?.articles.articleAtRow(indexPath.row) else {
+				guard let article = coordinator.articles.articleAtRow(indexPath.row) else {
 					return
 				}
 				
@@ -235,14 +227,14 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 
 	@objc func avatarDidBecomeAvailable(_ note: Notification) {
 		
-		guard navState?.showAvatars ?? false, let avatarURL = note.userInfo?[UserInfoKey.url] as? String else {
+		guard coordinator.showAvatars, let avatarURL = note.userInfo?[UserInfoKey.url] as? String else {
 			return
 		}
 		
 		performBlockAndRestoreSelection {
 			tableView.indexPathsForVisibleRows?.forEach { indexPath in
 				
-				guard let article = navState?.articles.articleAtRow(indexPath.row), let authors = article.authors, !authors.isEmpty else {
+				guard let article = coordinator.articles.articleAtRow(indexPath.row), let authors = article.authors, !authors.isEmpty else {
 					return
 				}
 				
@@ -258,7 +250,7 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 	}
 
 	@objc func imageDidBecomeAvailable(_ note: Notification) {
-		if navState?.showAvatars ?? false {
+		if coordinator.showAvatars {
 			queueReloadVisableCells()
 		}
 	}
@@ -287,7 +279,7 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 	
 	@objc func articleSelectionDidChange(_ note: Notification) {
 		
-		if let indexPath = navState?.currentArticleIndexPath {
+		if let indexPath = coordinator.currentArticleIndexPath {
 			if tableView.indexPathForSelectedRow != indexPath {
 				tableView.selectRow(at: indexPath, animated: true, scrollPosition: .middle)
 			}
@@ -323,10 +315,9 @@ class MasterTimelineViewController: ProgressTableViewController, UndoableCommand
 		if articleIDs.isEmpty {
 			return
 		}
-		if let indexes = navState?.indexesForArticleIDs(articleIDs) {
+		let indexes = coordinator.indexesForArticleIDs(articleIDs)
 		reloadVisibleCells(for: indexes)
 	}
-	}
 	
 	private func reloadVisibleCells(for indexes: IndexSet) {
 		performBlockAndRestoreSelection {
@@ -373,10 +364,10 @@ private extension MasterTimelineViewController {
 
 	func resetUI() {
 		
-		title = navState?.timelineName
-		navigationController?.title = navState?.timelineName
+		title = coordinator.timelineName
+		navigationController?.title = coordinator.timelineName
 		
-		if navState?.articles.count ?? 0 > 0 {
+		if coordinator.articles.count > 0 {
 			tableView.scrollToRow(at: IndexPath(row: 0, section: 0), at: .top, animated: false)
 		}
 		
@@ -385,8 +376,8 @@ private extension MasterTimelineViewController {
 	}
 	
 	func updateUI() {
-		markAllAsReadButton.isEnabled = navState?.isTimelineUnreadAvailable ?? false
-		firstUnreadButton.isEnabled = navState?.isTimelineUnreadAvailable ?? false
+		markAllAsReadButton.isEnabled = coordinator.isTimelineUnreadAvailable
+		firstUnreadButton.isEnabled = coordinator.isTimelineUnreadAvailable
 	}
 	
 	func configureTimelineCell(_ cell: MasterTimelineTableViewCell, article: Article) {
@@ -394,15 +385,15 @@ private extension MasterTimelineViewController {
 		let avatar = avatarFor(article)
 		let featuredImage = featuredImageFor(article)
 		
-		let showFeedNames = navState?.showFeedNames ?? false
-		let showAvatar = navState?.showAvatars ?? false && avatar != nil
+		let showFeedNames = coordinator.showFeedNames
+		let showAvatar = coordinator.showAvatars && avatar != nil
 		cell.cellData = MasterTimelineCellData(article: article, showFeedName: showFeedNames, feedName: article.feed?.nameForDisplay, avatar: avatar, showAvatar: showAvatar, featuredImage: featuredImage, numberOfLines: numberOfTextLines)
 		
 	}
 	
 	func avatarFor(_ article: Article) -> UIImage? {
 		
-		if !(navState?.showAvatars ?? false) {
+		if !coordinator.showAvatars {
 			return nil
 		}
 		

iOS/SceneDelegate.swift

@@ -8,7 +8,9 @@
 
 import UIKit
 
-class SceneDelegate: UIResponder, UIWindowSceneDelegate, UISplitViewControllerDelegate {
+class SceneDelegate: UIResponder, UIWindowSceneDelegate {
+	
+	var coordinator = AppCoordinator()
 	
     var window: UIWindow?
     
@@ -19,9 +21,13 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate, UISplitViewControllerDe
 		window!.tintColor = AppAssets.netNewsWireBlueColor
 
 		let splitViewController = UIStoryboard.main.instantiateInitialViewController() as! UISplitViewController
-		splitViewController.delegate = self
+		splitViewController.delegate = coordinator
 		window!.rootViewController = splitViewController
 
+		let masterNavigationController = splitViewController.viewControllers[0] as! UINavigationController
+		let masterFeedViewController = masterNavigationController.topViewController as! MasterFeedViewController
+		masterFeedViewController.coordinator = coordinator
+
 		let navigationController = splitViewController.viewControllers[splitViewController.viewControllers.count-1] as! UINavigationController
 		navigationController.topViewController!.navigationItem.leftBarButtonItem = splitViewController.displayModeButtonItem
 		
@@ -67,16 +73,4 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate, UISplitViewControllerDe
 //        return false
 //     }
 
-	// MARK: UISplitViewControllerDelegate
-	
-	func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController:UIViewController, onto primaryViewController:UIViewController) -> Bool {
-		guard let secondaryAsNavController = secondaryViewController as? UINavigationController else { return false }
-		guard let topAsDetailController = secondaryAsNavController.topViewController as? DetailViewController else { return false }
-		if topAsDetailController.navState?.currentArticle == nil {
-			// Return true to indicate that we have handled the collapse by doing nothing; the secondary controller will be discarded.
-			return true
-		}
-		return false
-	}
-	
 }