Add sidebar on iPadOS 14

Pachyderm/Model/List.swift

@@ -8,7 +8,7 @@
 
 import Foundation
 
-public class List: Decodable {
+public class List: Decodable, Equatable, Hashable {
     public let id: String
     public let title: String
     
@@ -16,6 +16,14 @@ public class List: Decodable {
         return .list(id: id)
     }
     
+    public static func ==(lhs: List, rhs: List) -> Bool {
+        return lhs.id == rhs.id
+    }
+    
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(id)
+    }
+    
     public static func getAccounts(_ list: List, range: RequestRange = .default) -> Request<[Account]> {
         var request = Request<[Account]>(method: .get, path: "/api/v1/lists/\(list.id)/accounts")
         request.range = range

Tusker.xcodeproj/project.pbxproj

@@ -174,6 +174,8 @@
 		D681E4D7246E32290053414F /* StatusActivityItemSource.swift in Sources */ = {isa = PBXBuildFile; fileRef = D681E4D6246E32290053414F /* StatusActivityItemSource.swift */; };
 		D681E4D9246E346E0053414F /* AccountActivityItemSource.swift in Sources */ = {isa = PBXBuildFile; fileRef = D681E4D8246E346E0053414F /* AccountActivityItemSource.swift */; };
 		D68232F72464F4FD00325FB8 /* ComposeDrawingViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D68232F62464F4FD00325FB8 /* ComposeDrawingViewController.swift */; };
+		D68E525B24A3D77E0054355A /* TuskerRootViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D68E525A24A3D77E0054355A /* TuskerRootViewController.swift */; };
+		D68E525D24A3E8F00054355A /* SearchViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D68E525C24A3E8F00054355A /* SearchViewController.swift */; };
 		D68FEC4F232C5BC300C84F23 /* SegmentedPageViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D68FEC4E232C5BC300C84F23 /* SegmentedPageViewController.swift */; };
 		D693DE5723FE1A6A0061E07D /* EnhancedNavigationViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D693DE5623FE1A6A0061E07D /* EnhancedNavigationViewController.swift */; };
 		D693DE5923FE24310061E07D /* InteractivePushTransition.swift in Sources */ = {isa = PBXBuildFile; fileRef = D693DE5823FE24300061E07D /* InteractivePushTransition.swift */; };
@@ -249,6 +251,8 @@
 		D6E6F26521604242006A8599 /* CharacterCounterTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6E6F26421604242006A8599 /* CharacterCounterTests.swift */; };
 		D6EBF01523C55C0900AE061B /* UIApplication+Scenes.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6EBF01423C55C0900AE061B /* UIApplication+Scenes.swift */; };
 		D6EBF01723C55E0D00AE061B /* UISceneSession+MastodonController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6EBF01623C55E0D00AE061B /* UISceneSession+MastodonController.swift */; };
+		D6F0B12B24A3071C001E48C3 /* MainSplitViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6F0B12A24A3071C001E48C3 /* MainSplitViewController.swift */; };
+		D6F0B17524A3A1AA001E48C3 /* MainSidebarViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6F0B17424A3A1AA001E48C3 /* MainSidebarViewController.swift */; };
 		D6F1F84D2193B56E00F5FE67 /* Cache.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6F1F84C2193B56E00F5FE67 /* Cache.swift */; };
 		D6F2E965249E8BFD005846BB /* CrashReporterViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6F2E963249E8BFD005846BB /* CrashReporterViewController.swift */; };
 		D6F2E966249E8BFD005846BB /* CrashReporterViewController.xib in Resources */ = {isa = PBXBuildFile; fileRef = D6F2E964249E8BFD005846BB /* CrashReporterViewController.xib */; };
@@ -481,6 +485,8 @@
 		D681E4D6246E32290053414F /* StatusActivityItemSource.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusActivityItemSource.swift; sourceTree = "<group>"; };
 		D681E4D8246E346E0053414F /* AccountActivityItemSource.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AccountActivityItemSource.swift; sourceTree = "<group>"; };
 		D68232F62464F4FD00325FB8 /* ComposeDrawingViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeDrawingViewController.swift; sourceTree = "<group>"; };
+		D68E525A24A3D77E0054355A /* TuskerRootViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TuskerRootViewController.swift; sourceTree = "<group>"; };
+		D68E525C24A3E8F00054355A /* SearchViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SearchViewController.swift; sourceTree = "<group>"; };
 		D68FEC4E232C5BC300C84F23 /* SegmentedPageViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SegmentedPageViewController.swift; sourceTree = "<group>"; };
 		D693DE5623FE1A6A0061E07D /* EnhancedNavigationViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EnhancedNavigationViewController.swift; sourceTree = "<group>"; };
 		D693DE5823FE24300061E07D /* InteractivePushTransition.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InteractivePushTransition.swift; sourceTree = "<group>"; };
@@ -558,6 +564,8 @@
 		D6E6F26421604242006A8599 /* CharacterCounterTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CharacterCounterTests.swift; sourceTree = "<group>"; };
 		D6EBF01423C55C0900AE061B /* UIApplication+Scenes.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UIApplication+Scenes.swift"; sourceTree = "<group>"; };
 		D6EBF01623C55E0D00AE061B /* UISceneSession+MastodonController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UISceneSession+MastodonController.swift"; sourceTree = "<group>"; };
+		D6F0B12A24A3071C001E48C3 /* MainSplitViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainSplitViewController.swift; sourceTree = "<group>"; };
+		D6F0B17424A3A1AA001E48C3 /* MainSidebarViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MainSidebarViewController.swift; sourceTree = "<group>"; };
 		D6F1F84C2193B56E00F5FE67 /* Cache.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Cache.swift; sourceTree = "<group>"; };
 		D6F2E963249E8BFD005846BB /* CrashReporterViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = CrashReporterViewController.swift; sourceTree = "<group>"; };
 		D6F2E964249E8BFD005846BB /* CrashReporterViewController.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = CrashReporterViewController.xib; sourceTree = "<group>"; };
@@ -896,7 +904,10 @@
 		D641C782213DD7F0004B4513 /* Main */ = {
 			isa = PBXGroup;
 			children = (
+				D6F0B12A24A3071C001E48C3 /* MainSplitViewController.swift */,
 				04DACE8B212CB14B009840C4 /* MainTabBarViewController.swift */,
+				D6F0B17424A3A1AA001E48C3 /* MainSidebarViewController.swift */,
+				D68E525A24A3D77E0054355A /* TuskerRootViewController.swift */,
 			);
 			path = Main;
 			sourceTree = "<group>";
@@ -1190,6 +1201,7 @@
 		D6BC9DD8232D8BCA002CA326 /* Search */ = {
 			isa = PBXGroup;
 			children = (
+				D68E525C24A3E8F00054355A /* SearchViewController.swift */,
 				D6BC9DD9232D8BE5002CA326 /* SearchResultsViewController.swift */,
 			);
 			path = Search;
@@ -1703,6 +1715,7 @@
 				D6757A822157E8FA00721E32 /* XCBSession.swift in Sources */,
 				D6EBF01723C55E0D00AE061B /* UISceneSession+MastodonController.swift in Sources */,
 				04DACE8C212CB14B009840C4 /* MainTabBarViewController.swift in Sources */,
+				D68E525D24A3E8F00054355A /* SearchViewController.swift in Sources */,
 				D6AEBB412321642700E5038B /* SendMesasgeActivity.swift in Sources */,
 				D6BC9DB1232C61BC002CA326 /* NotificationsPageViewController.swift in Sources */,
 				D6969E9E240C81B9002843CE /* NSTextAttachment+Emoji.swift in Sources */,
@@ -1734,6 +1747,7 @@
 				D627944D23A9A03D00D38C68 /* ListTimelineViewController.swift in Sources */,
 				D6945C3823AC739F005C403C /* InstanceTimelineViewController.swift in Sources */,
 				D60309B52419D4F100A465FF /* ComposeAttachmentsViewController.swift in Sources */,
+				D68E525B24A3D77E0054355A /* TuskerRootViewController.swift in Sources */,
 				D62D2422217AA7E1005076CC /* UserActivityManager.swift in Sources */,
 				D6CA6A92249FAD8900AD45C1 /* AudioSessionHelper.swift in Sources */,
 				D60D2B8223844C71001B87A3 /* BaseStatusTableViewCell.swift in Sources */,
@@ -1773,6 +1787,7 @@
 				D6AEBB4523216AF800E5038B /* FollowAccountActivity.swift in Sources */,
 				D6EBF01523C55C0900AE061B /* UIApplication+Scenes.swift in Sources */,
 				D6538945214D6D7500E3CEFC /* TableViewSwipeActionProvider.swift in Sources */,
+				D6F0B17524A3A1AA001E48C3 /* MainSidebarViewController.swift in Sources */,
 				D6E0DC8E216EDF1E00369478 /* Previewing.swift in Sources */,
 				D6BED174212667E900F02DA0 /* TimelineStatusTableViewCell.swift in Sources */,
 				0427033822B30F5F000D31B6 /* BehaviorPrefsView.swift in Sources */,
@@ -1834,6 +1849,7 @@
 				D64D8CA92463B494006B0BAA /* CachedDictionary.swift in Sources */,
 				D6757A7C2157E01900721E32 /* XCBManager.swift in Sources */,
 				D6F1F84D2193B56E00F5FE67 /* Cache.swift in Sources */,
+				D6F0B12B24A3071C001E48C3 /* MainSplitViewController.swift in Sources */,
 				0427037C22B316B9000D31B6 /* SilentActionPrefs.swift in Sources */,
 				D6AEBB3E2321638100E5038B /* UIActivity+Types.swift in Sources */,
 				D61AC1D5232E9FA600C54D2D /* InstanceSelectorTableViewController.swift in Sources */,

Tusker/SceneDelegate.swift

@@ -157,8 +157,13 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
         mastodonController.getOwnAccount()
         mastodonController.getOwnInstance()
         
-        let tabBarController = MainTabBarViewController(mastodonController: mastodonController)
+        let rootController: UIViewController
-        window!.rootViewController = tabBarController
+        if #available(iOS 14.0, *) {
+            rootController = MainSplitViewController(mastodonController: mastodonController)
+        } else {
+            rootController = MainTabBarViewController(mastodonController: mastodonController)
+        }
+        window!.rootViewController = rootController
     }
     
     func showOnboardingUI() {

Tusker/Screens/Explore/ExploreViewController.swift

@@ -90,9 +90,7 @@ class ExploreViewController: EnhancedTableViewController {
         snapshot.appendItems(SavedDataManager.shared.sortedHashtags(for: account).map { .savedHashtag($0) } + [.addSavedHashtag], toSection: .savedHashtags)
         snapshot.appendItems(SavedDataManager.shared.savedInstances(for: account).map { .savedInstance($0) } + [.findInstance], toSection: .savedInstances)
         // the initial, static items should not be displayed with an animation
-        UIView.performWithoutAnimation {
+        dataSource.apply(snapshot, animatingDifferences: false)
-            dataSource.apply(snapshot)
-        }
 
         resultsController = SearchResultsViewController(mastodonController: mastodonController)
         resultsController.exploreNavigationController = self.navigationController!

Tusker/Screens/Main/MainSidebarViewController.swift

@@ -0,0 +1,344 @@
+//
+//  MainSidebarViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/24/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+import Pachyderm
+
+@available(iOS 14.0, *)
+protocol MainSidebarViewControllerDelegate: class {
+    func sidebarRequestPresentCompose(_ sidebarViewController: MainSidebarViewController)
+    func sidebar(_ sidebarViewController: MainSidebarViewController, didSelectItem item: MainSidebarViewController.Item)
+}
+
+@available(iOS 14.0, *)
+class MainSidebarViewController: UIViewController {
+    
+    weak var mastodonController: MastodonController!
+    
+    weak var sidebarDelegate: MainSidebarViewControllerDelegate?
+    
+    var collectionView: UICollectionView!
+    var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
+
+    init(mastodonController: MastodonController) {
+        self.mastodonController = mastodonController
+        
+        super.init(nibName: nil, bundle: nil)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        navigationItem.title = "Tusker"
+        navigationItem.largeTitleDisplayMode = .always
+        navigationController!.navigationBar.prefersLargeTitles = true
+        
+        let layout = UICollectionViewCompositionalLayout.list(using: .init(appearance: .sidebar))
+        collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)
+        collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
+        collectionView.backgroundColor = .systemGroupedBackground
+        collectionView.delegate = self
+        view.addSubview(collectionView)
+        
+        dataSource = createDataSource()
+        
+        applyInitialSnapshot()
+        
+        select(.tab(.timelines), animated: false)
+        
+        NotificationCenter.default.addObserver(self, selector: #selector(reloadSavedHashtags), name: .savedHashtagsChanged, object: nil)
+        NotificationCenter.default.addObserver(self, selector: #selector(reloadSavedInstances), name: .savedInstancesChanged, object: nil)
+    }
+    
+    func select(_ item: Item, animated: Bool) {
+        guard let indexPath = dataSource.indexPath(for: item) else { return }
+        collectionView.selectItem(at: indexPath, animated: animated, scrollPosition: .top)
+    }
+    
+    private func createDataSource() -> UICollectionViewDiffableDataSource<Section, Item> {
+        let listCell = UICollectionView.CellRegistration<UICollectionViewListCell, Item> { (cell, indexPath, item) in
+            var config = cell.defaultContentConfiguration()
+            config.text = item.title
+            if let imageName = item.imageName {
+                config.image = UIImage(systemName: imageName)
+            }
+            cell.contentConfiguration = config
+        }
+        
+        let outlineHeaderCell = UICollectionView.CellRegistration<UICollectionViewListCell, Item> { (cell, indexPath, item) in
+            var config = cell.defaultContentConfiguration()
+            config.attributedText = NSAttributedString(string: item.title, attributes: [
+                .font: UIFont.boldSystemFont(ofSize: 21)
+            ])
+            cell.contentConfiguration = config
+            cell.accessories = [.outlineDisclosure(options: .init(style: .header))]
+        }
+        
+        return UICollectionViewDiffableDataSource<Section, Item>(collectionView: collectionView, cellProvider: { (collectionView, indexPath, item) -> UICollectionViewCell? in
+            if item.hasChildren {
+                return collectionView.dequeueConfiguredReusableCell(using: outlineHeaderCell, for: indexPath, item: item)
+            } else {
+                return collectionView.dequeueConfiguredReusableCell(using: listCell, for: indexPath, item: item)
+            }
+        })
+    }
+
+    private func applyInitialSnapshot() {
+        var snapshot = NSDiffableDataSourceSnapshot<Section, Item>()
+        snapshot.appendSections(Section.allCases)
+        snapshot.appendItems([
+            .tab(.timelines),
+            .tab(.notifications),
+            .search,
+            .bookmarks,
+            .tab(.myProfile)
+        ], toSection: .tabs)
+        snapshot.appendItems([
+            .tab(.compose)
+        ], toSection: .compose)
+        dataSource.apply(snapshot, animatingDifferences: false)
+        
+        reloadLists()
+        reloadSavedHashtags()
+        reloadSavedInstances()
+    }
+    
+    private func reloadLists() {
+        let request = Client.getLists()
+        mastodonController.run(request) { [weak self] (response) in
+            guard let self = self, case let .success(lists, _) = response else { return }
+            
+            var exploreSnapshot = NSDiffableDataSourceSectionSnapshot<Item>()
+            exploreSnapshot.append([.listsHeader])
+            exploreSnapshot.expand([.listsHeader])
+            exploreSnapshot.append(lists.map { .list($0) }, to: .listsHeader)
+            exploreSnapshot.append([.addList], to: .listsHeader)
+            DispatchQueue.main.async {
+                self.dataSource.apply(exploreSnapshot, to: .lists)
+            }
+        }
+    }
+    
+    @objc private func reloadSavedHashtags() {
+        var hashtagsSnapshot = NSDiffableDataSourceSectionSnapshot<Item>()
+        hashtagsSnapshot.append([.savedHashtagsHeader])
+        hashtagsSnapshot.expand([.savedHashtagsHeader])
+        let sortedHashtags = SavedDataManager.shared.sortedHashtags(for: mastodonController.accountInfo!)
+        hashtagsSnapshot.append(sortedHashtags.map { .savedHashtag($0) }, to: .savedHashtagsHeader)
+        hashtagsSnapshot.append([.addSavedHashtag], to: .savedHashtagsHeader)
+        self.dataSource.apply(hashtagsSnapshot, to: .savedHashtags, animatingDifferences: false)
+    }
+    
+    @objc private func reloadSavedInstances() {
+        var instancesSnapshot = NSDiffableDataSourceSectionSnapshot<Item>()
+        instancesSnapshot.append([.savedInstancesHeader])
+        instancesSnapshot.expand([.savedInstancesHeader])
+        let sortedInstances = SavedDataManager.shared.savedInstances(for: mastodonController.accountInfo!)
+        instancesSnapshot.append(sortedInstances.map { .savedInstance($0) }, to: .savedInstancesHeader)
+        instancesSnapshot.append([.addSavedInstance], to: .savedInstancesHeader)
+        self.dataSource.apply(instancesSnapshot, to: .savedInstances, animatingDifferences: false)
+    }
+
+    // todo: deduplicate with ExploreViewController
+    private func showAddList() {
+        let alert = UIAlertController(title: "New List", message: "Choose a title for your new list", preferredStyle: .alert)
+        alert.addTextField(configurationHandler: nil)
+        alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
+        alert.addAction(UIAlertAction(title: "Create List", style: .default, handler: { (_) in
+            guard let title = alert.textFields?.first?.text else {
+                fatalError()
+            }
+            
+            let request = Client.createList(title: title)
+            self.mastodonController.run(request) { (response) in
+                guard case let .success(list, _) = response else { fatalError() }
+                
+                self.reloadLists()
+                
+                DispatchQueue.main.async {
+                    self.sidebarDelegate?.sidebar(self, didSelectItem: .list(list))
+                }
+            }
+        }))
+        present(alert, animated: true)
+    }
+    
+    // todo: deduplicate with ExploreViewController
+    private func showAddSavedHashtag() {
+        let navController = EnhancedNavigationViewController(rootViewController: AddSavedHashtagViewController(mastodonController: mastodonController))
+        present(navController, animated: true)
+    }
+    
+    // todo: deduplicate with ExploreViewController
+    private func showAddSavedInstance() {
+        let findController = FindInstanceViewController(parentMastodonController: mastodonController)
+        findController.instanceTimelineDelegate = self
+        let navController = EnhancedNavigationViewController(rootViewController: findController)
+        present(navController, animated: true)
+    }
+    
+}
+
+@available(iOS 14.0, *)
+extension MainSidebarViewController {
+    enum Section: Int, Hashable, CaseIterable {
+        case tabs
+        case compose
+        case lists
+        case savedHashtags
+        case savedInstances
+    }
+    enum Item: Hashable {
+        case tab(MainTabBarViewController.Tab)
+        case search, bookmarks
+        case listsHeader, list(List), addList
+        case savedHashtagsHeader, savedHashtag(Hashtag), addSavedHashtag
+        case savedInstancesHeader, savedInstance(URL), addSavedInstance
+        
+        var title: String {
+            switch self {
+            case let .tab(tab):
+                return tab.title
+            case .search:
+                return "Search"
+            case .bookmarks:
+                return "Bookmarks"
+            case .listsHeader:
+                return "Lists"
+            case let .list(list):
+                return list.title
+            case .addList:
+                return "New List..."
+            case .savedHashtagsHeader:
+                return "Saved Hashtags"
+            case let .savedHashtag(hashtag):
+                return hashtag.name
+            case .addSavedHashtag:
+                return "Save Hashtag..."
+            case .savedInstancesHeader:
+                return "Saved Instances"
+            case let .savedInstance(url):
+                return url.host!
+            case .addSavedInstance:
+                return "Find An Instance..."
+            }
+        }
+        
+        var imageName: String? {
+            switch self {
+            case let .tab(tab):
+                return tab.imageName
+            case .search:
+                return "magnifyingglass"
+            case .bookmarks:
+                return "bookmark"
+            case .list(_):
+                return "list.bullet"
+            case .savedHashtag(_):
+                return "number"
+            case .savedInstance(_):
+                return "globe"
+            case .listsHeader, .savedHashtagsHeader, .savedInstancesHeader:
+                return nil
+            case .addList, .addSavedHashtag, .addSavedInstance:
+                return "plus"
+            }
+        }
+        
+        var hasChildren: Bool {
+            switch self {
+            case .listsHeader, .savedHashtagsHeader, .savedInstancesHeader:
+                return true
+            default:
+                return false
+            }
+        }
+    }
+}
+
+fileprivate extension MainTabBarViewController.Tab {
+    var title: String {
+        switch self {
+        case .timelines:
+            return "Home"
+        case .notifications:
+            return "Notifications"
+        case .compose:
+            return "Compose"
+        case .explore:
+            return "Explore"
+        case .myProfile:
+            return "My Profile"
+        }
+    }
+    
+    var imageName: String? {
+        switch self {
+        case .timelines:
+            return "house"
+        case .notifications:
+            return "bell"
+        case .compose:
+            return "pencil"
+        case .explore:
+            return "magnifyingglass"
+        case .myProfile:
+            // todo: use user avatar image
+            return "person"
+        }
+    }
+}
+
+@available(iOS 14.0, *)
+extension MainSidebarViewController: UICollectionViewDelegate {
+    func collectionView(_ collectionView: UICollectionView, shouldSelectItemAt indexPath: IndexPath) -> Bool {
+        guard let item = dataSource.itemIdentifier(for: indexPath) else {
+            return false
+        }
+        switch item {
+        case .tab(.compose):
+            sidebarDelegate?.sidebarRequestPresentCompose(self)
+            return false
+        case .addList:
+            showAddList()
+            return false
+        case .addSavedHashtag:
+            showAddSavedHashtag()
+            return false
+        case .addSavedInstance:
+            showAddSavedInstance()
+            return false
+        default:
+            return true
+        }
+    }
+    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
+        guard let item = dataSource.itemIdentifier(for: indexPath) else {
+            collectionView.deselectItem(at: indexPath, animated: true)
+            return
+        }
+        sidebarDelegate?.sidebar(self, didSelectItem: item)
+    }
+}
+
+@available(iOS 14.0, *)
+extension MainSidebarViewController: InstanceTimelineViewControllerDelegate {
+    func didSaveInstance(url: URL) {
+        dismiss(animated: true) {
+            self.sidebarDelegate?.sidebar(self, didSelectItem: .savedInstance(url))
+        }
+    }
+    
+    func didUnsaveInstance(url: URL) {
+        dismiss(animated: true)
+    }
+}

Tusker/Screens/Main/MainSplitViewController.swift

@@ -0,0 +1,116 @@
+//
+//  MainSplitViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/23/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+@available(iOS 14.0, *)
+class MainSplitViewController: UISplitViewController {
+
+    weak var mastodonController: MastodonController!
+    
+    private var sidebar: MainSidebarViewController!
+    
+    private var detailViewControllers: [MainSidebarViewController.Item: UIViewController] = [:]
+    
+    init(mastodonController: MastodonController) {
+        self.mastodonController = mastodonController
+        
+        super.init(style: .doubleColumn)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+        
+        preferredDisplayMode = .oneBesideSecondary
+        preferredSplitBehavior = .tile
+        presentsWithGesture = false
+        showsSecondaryOnlyButton = false
+        
+        sidebar = MainSidebarViewController(mastodonController: mastodonController)
+        sidebar.sidebarDelegate = self
+        setViewController(sidebar, for: .primary)
+        select(item: .tab(.timelines))
+        setViewController(MainTabBarViewController(mastodonController: mastodonController), for: .compact)
+    }
+    
+    func select(item: MainSidebarViewController.Item) {
+        let itemController = getOrCreateDetailViewController(item: item)
+        setViewController(itemController, for: .secondary)
+    }
+    
+    func getOrCreateDetailViewController(item: MainSidebarViewController.Item) -> UIViewController? {
+        if let existing = detailViewControllers[item] {
+            return existing
+        } else {
+            guard let new = item.createRootViewController(mastodonController) else { return nil }
+            let nav = EnhancedNavigationViewController(rootViewController: new)
+            
+            // Prevents the navigation bar from going transparent when switching sidebar sections.
+            nav.navigationBar.scrollEdgeAppearance = nav.navigationBar.standardAppearance
+            
+            detailViewControllers[item] = nav
+            return nav
+        }
+    }
+
+}
+
+@available(iOS 14.0, *)
+extension MainSplitViewController: MainSidebarViewControllerDelegate {
+    func sidebarRequestPresentCompose(_ sidebarViewController: MainSidebarViewController) {
+        presentCompose()
+    }
+    
+    func sidebar(_ sidebarViewController: MainSidebarViewController, didSelectItem item: MainSidebarViewController.Item) {
+        select(item: item)
+    }
+}
+
+@available(iOS 14.0, *)
+fileprivate extension MainSidebarViewController.Item {
+    func createRootViewController(_ mastodonController: MastodonController) -> UIViewController? {
+        switch self {
+        case let .tab(tab):
+            return tab.createViewController(mastodonController)
+        case .search:
+            return SearchViewController(mastodonController: mastodonController)
+        case .bookmarks:
+            return BookmarksTableViewController(mastodonController: mastodonController)
+        case let .list(list):
+            return ListTimelineViewController(for: list, mastodonController: mastodonController)
+        case let .savedHashtag(hashtag):
+            return HashtagTimelineViewController(for: hashtag, mastodonController: mastodonController)
+        case let .savedInstance(url):
+            return InstanceTimelineViewController(for: url, parentMastodonController: mastodonController)
+        default:
+            return nil
+        }
+    }
+}
+
+@available(iOS 14.0, *)
+extension MainSplitViewController: TuskerRootViewController {
+    func presentCompose() {
+        let compose = ComposeViewController(mastodonController: mastodonController)
+        let navigationController = EnhancedNavigationViewController(rootViewController: compose)
+        navigationController.presentationController?.delegate = compose
+        present(navigationController, animated: true)
+    }
+    
+    func select(tab: MainTabBarViewController.Tab) {
+        if tab == .compose {
+            presentCompose()
+        } else {
+            select(item: .tab(tab))
+        }
+    }
+}

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -12,6 +12,8 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
     
     weak var mastodonController: MastodonController!
     
+    private var composePlaceholder: UIViewController!
+
     override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
         if UIDevice.current.userInterfaceIdiom == .phone {
             return .portrait
@@ -35,12 +37,16 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
 
         self.delegate = self
         
+        composePlaceholder = UIViewController()
+        composePlaceholder.title = "Compose"
+        composePlaceholder.tabBarItem.image = UIImage(systemName: "pencil")
+        
         viewControllers = [
-            embedInNavigationController(TimelinesPageViewController(mastodonController: mastodonController)),
+            embedInNavigationController(Tab.timelines.createViewController(mastodonController)),
-            embedInNavigationController(NotificationsPageViewController(mastodonController: mastodonController)),
+            embedInNavigationController(Tab.notifications.createViewController(mastodonController)),
-            ComposeViewController(mastodonController: mastodonController),
+            composePlaceholder,
-            embedInNavigationController(ExploreViewController(mastodonController: mastodonController)),
+            embedInNavigationController(Tab.explore.createViewController(mastodonController)),
-            embedInNavigationController(MyProfileTableViewController(mastodonController: mastodonController)),
+            embedInNavigationController(Tab.myProfile.createViewController(mastodonController)),
         ]
     }
     
@@ -53,37 +59,39 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
     }
     
     func tabBarController(_ tabBarController: UITabBarController, shouldSelect viewController: UIViewController) -> Bool {
-        if viewController is ComposeViewController {
+        if viewController == composePlaceholder {
             presentCompose()
             return false
         }
         return true
     }
-    
-    func presentCompose() {
-        let compose = ComposeViewController(mastodonController: mastodonController)
-        let navigationController = embedInNavigationController(compose)
-        navigationController.presentationController?.delegate = compose
-        present(navigationController, animated: true)
-    }
 }
 
 extension MainTabBarViewController {
-    enum Tab: Int {
+    enum Tab: Int, Hashable, CaseIterable {
         case timelines
         case notifications
         case compose
         case explore
         case myProfile
+        
+        func createViewController(_ mastodonController: MastodonController) -> UIViewController {
+            switch self {
+            case .timelines:
+                return TimelinesPageViewController(mastodonController: mastodonController)
+            case .notifications:
+                return NotificationsPageViewController(mastodonController: mastodonController)
+            case .compose:
+                return ComposeViewController(mastodonController: mastodonController)
+            case .explore:
+                return ExploreViewController(mastodonController: mastodonController)
+            case .myProfile:
+                return MyProfileTableViewController(mastodonController: mastodonController)
+            }
+        }
     }
     
-    func select(tab: Tab) {
+    
-        if tab == .compose {
-            presentCompose()
-        } else {
-            selectedIndex = tab.rawValue
-        }
-    }
     
     func getTabController(tab: Tab) -> UIViewController? {
         if tab == .compose {
@@ -93,3 +101,20 @@ extension MainTabBarViewController {
         }
     }
 }
+
+extension MainTabBarViewController: TuskerRootViewController {
+    func presentCompose() {
+        let compose = ComposeViewController(mastodonController: mastodonController)
+        let navigationController = embedInNavigationController(compose)
+        navigationController.presentationController?.delegate = compose
+        present(navigationController, animated: true)
+    }
+    
+    func select(tab: Tab) {
+        if tab == .compose {
+            presentCompose()
+        } else {
+            selectedIndex = tab.rawValue
+        }
+    }
+}

Tusker/Screens/Main/TuskerRootViewController.swift

@@ -0,0 +1,14 @@
+//
+//  TuskerRootViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/24/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+protocol TuskerRootViewController: UIViewController {
+    func presentCompose()
+    func select(tab: MainTabBarViewController.Tab)
+}

Tusker/Screens/Search/SearchResultsViewController.swift

@@ -28,7 +28,7 @@ extension SearchResultsViewControllerDelegate {
 
 class SearchResultsViewController: EnhancedTableViewController {
 
-    let mastodonController: MastodonController!
+    weak var mastodonController: MastodonController!
     
     weak var exploreNavigationController: UINavigationController?
     weak var delegate: SearchResultsViewControllerDelegate?

Tusker/Screens/Search/SearchViewController.swift

@@ -0,0 +1,46 @@
+//
+//  SearchViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 6/24/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+class SearchViewController: UIViewController {
+
+    weak var mastodonController: MastodonController!
+    
+    var resultsController: SearchResultsViewController!
+    var searchController: UISearchController!
+    
+    init(mastodonController: MastodonController) {
+        self.mastodonController = mastodonController
+        
+        super.init(nibName: nil, bundle: nil)
+        
+        title = NSLocalizedString("Search", comment: "search tab title")
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        resultsController = SearchResultsViewController(mastodonController: mastodonController)
+        resultsController.exploreNavigationController = self.navigationController
+        searchController = UISearchController(searchResultsController: resultsController)
+        searchController.searchResultsUpdater = resultsController
+        searchController.searchBar.autocapitalizationType = .none
+        searchController.searchBar.delegate = resultsController
+        definesPresentationContext = true
+        
+        navigationItem.searchController = searchController
+        navigationItem.hidesSearchBarWhenScrolling = false
+    }
+    
+
+}