Fix crash when replying to post with preformatted text

UIDeferredMenuElement completion handler should only be called from the
main thread

Tusker.xcodeproj/project.pbxproj

@@ -134,6 +134,8 @@
 		D6412B0B24B0D4C600F5412E /* ProfileHeaderView.xib in Resources */ = {isa = PBXBuildFile; fileRef = D6412B0A24B0D4C600F5412E /* ProfileHeaderView.xib */; };
 		D6412B0D24B0D4CF00F5412E /* ProfileHeaderView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6412B0C24B0D4CF00F5412E /* ProfileHeaderView.swift */; };
 		D641C77F213DC78A004B4513 /* InlineTextAttachment.swift in Sources */ = {isa = PBXBuildFile; fileRef = D641C77E213DC78A004B4513 /* InlineTextAttachment.swift */; };
+		D6420AEE26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6420AEC26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.swift */; };
+		D6420AEF26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = D6420AED26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.xib */; };
 		D6434EB3215B1856001A919A /* XCBRequest.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6434EB2215B1856001A919A /* XCBRequest.swift */; };
 		D646C956213B365700269FB5 /* LargeImageExpandAnimationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D646C955213B365700269FB5 /* LargeImageExpandAnimationController.swift */; };
 		D646C958213B367000269FB5 /* LargeImageShrinkAnimationController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D646C957213B367000269FB5 /* LargeImageShrinkAnimationController.swift */; };
@@ -535,6 +537,8 @@
 		D6412B0A24B0D4C600F5412E /* ProfileHeaderView.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = ProfileHeaderView.xib; sourceTree = "<group>"; };
 		D6412B0C24B0D4CF00F5412E /* ProfileHeaderView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ProfileHeaderView.swift; sourceTree = "<group>"; };
 		D641C77E213DC78A004B4513 /* InlineTextAttachment.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = InlineTextAttachment.swift; sourceTree = "<group>"; };
+		D6420AEC26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PublicTimelineDescriptionTableViewCell.swift; sourceTree = "<group>"; };
+		D6420AED26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = PublicTimelineDescriptionTableViewCell.xib; sourceTree = "<group>"; };
 		D6434EB2215B1856001A919A /* XCBRequest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = XCBRequest.swift; sourceTree = "<group>"; };
 		D646C955213B365700269FB5 /* LargeImageExpandAnimationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LargeImageExpandAnimationController.swift; sourceTree = "<group>"; };
 		D646C957213B367000269FB5 /* LargeImageShrinkAnimationController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = LargeImageShrinkAnimationController.swift; sourceTree = "<group>"; };
@@ -1240,6 +1244,15 @@
 			path = Notifications;
 			sourceTree = "<group>";
 		};
+		D6420AEB26BED17500ED8175 /* Timeline Description Cell */ = {
+			isa = PBXGroup;
+			children = (
+				D6420AEC26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.swift */,
+				D6420AED26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.xib */,
+			);
+			path = "Timeline Description Cell";
+			sourceTree = "<group>";
+		};
 		D646C954213B364600269FB5 /* Transitions */ = {
 			isa = PBXGroup;
 			children = (
@@ -1470,6 +1483,7 @@
 				D611C2CC232DC5FC00C86A49 /* Hashtag Cell */,
 				D61AC1DA232EA43100C54D2D /* Instance Cell */,
 				D6DEA0DB268400AF00FE896A /* Confirm Load More Cell */,
+				D6420AEB26BED17500ED8175 /* Timeline Description Cell */,
 			);
 			path = Views;
 			sourceTree = "<group>";
@@ -1886,6 +1900,7 @@
 				D6412B0B24B0D4C600F5412E /* ProfileHeaderView.xib in Resources */,
 				D6C82B5725C5F3F20017F1E6 /* ExpandThreadTableViewCell.xib in Resources */,
 				D6D4DDDA212518A200E1C4BB /* LaunchScreen.storyboard in Resources */,
+				D6420AEF26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.xib in Resources */,
 				D6E57FA325C26FAB00341037 /* Localizable.stringsdict in Resources */,
 				D6B053AC23BD2F1400A066FA /* AssetCollectionViewCell.xib in Resources */,
 				D6D4DDD7212518A200E1C4BB /* Assets.xcassets in Resources */,
@@ -2147,6 +2162,7 @@
 				D6538945214D6D7500E3CEFC /* TableViewSwipeActionProvider.swift in Sources */,
 				D6F0B17524A3A1AA001E48C3 /* MainSidebarViewController.swift in Sources */,
 				D622757424EDF1CD00B82A16 /* ComposeAttachmentsList.swift in Sources */,
+				D6420AEE26BED18B00ED8175 /* PublicTimelineDescriptionTableViewCell.swift in Sources */,
 				D6E0DC8E216EDF1E00369478 /* Previewing.swift in Sources */,
 				D6BED174212667E900F02DA0 /* TimelineStatusTableViewCell.swift in Sources */,
 				D69693F42585941A00F4E116 /* UIWindowSceneDelegate+Close.swift in Sources */,
@@ -2509,6 +2525,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_ACTIVE_COMPILATION_CONDITIONS = DEBUG;
 				SWIFT_OPTIMIZATION_LEVEL = "-Onone";
+				SWIFT_OPTIMIZE_OBJECT_LIFETIME = YES;
 			};
 			name = Debug;
 		};
@@ -2565,6 +2582,7 @@
 				SDKROOT = iphoneos;
 				SWIFT_COMPILATION_MODE = wholemodule;
 				SWIFT_OPTIMIZATION_LEVEL = "-O";
+				SWIFT_OPTIMIZE_OBJECT_LIFETIME = YES;
 				VALIDATE_PRODUCT = YES;
 			};
 			name = Release;

Tusker/Preferences/Preferences.swift

@@ -67,6 +67,9 @@ class Preferences: Codable, ObservableObject {
         
         self.silentActions = try container.decode([String: Permission].self, forKey: .silentActions)
         self.statusContentType = try container.decode(StatusContentType.self, forKey: .statusContentType)
+        
+        self.hasShownLocalTimelineDescription = try container.decodeIfPresent(Bool.self, forKey: .hasShownLocalTimelineDescription) ?? false
+        self.hasShownFederatedTimelineDescription = try container.decodeIfPresent(Bool.self, forKey: .hasShownFederatedTimelineDescription) ?? false
     }
     
     func encode(to encoder: Encoder) throws {
@@ -102,6 +105,9 @@ class Preferences: Codable, ObservableObject {
         
         try container.encode(silentActions, forKey: .silentActions)
         try container.encode(statusContentType, forKey: .statusContentType)
+        
+        try container.encode(hasShownLocalTimelineDescription, forKey: .hasShownLocalTimelineDescription)
+        try container.encode(hasShownFederatedTimelineDescription, forKey: .hasShownFederatedTimelineDescription)
     }
     
     // MARK: Appearance
@@ -141,6 +147,10 @@ class Preferences: Codable, ObservableObject {
     @Published var silentActions: [String: Permission] = [:]
     @Published var statusContentType: StatusContentType = .plain
     
+    // MARK:
+    @Published var hasShownLocalTimelineDescription = false
+    @Published var hasShownFederatedTimelineDescription = false
+    
     private enum CodingKeys: String, CodingKey {
         case theme
         case avatarStyle
@@ -172,6 +182,9 @@ class Preferences: Codable, ObservableObject {
         
         case silentActions
         case statusContentType
+        
+        case hasShownLocalTimelineDescription
+        case hasShownFederatedTimelineDescription
     }
     
 }

Tusker/Screens/Onboarding/InstanceSelectorTableViewController.swift

@@ -50,6 +50,11 @@ class InstanceSelectorTableViewController: UITableViewController {
     override func viewDidLoad() {
         super.viewDidLoad()
         
+        // disable transparent background when scrolled to top because it gets weird with animating table items in and out
+        let appearance = UINavigationBarAppearance()
+        appearance.configureWithDefaultBackground()
+        navigationItem.scrollEdgeAppearance = appearance
+
         tableView.register(UINib(nibName: "InstanceTableViewCell", bundle: .main), forCellReuseIdentifier: instanceCell)
         
         tableView.rowHeight = UITableView.automaticDimension
@@ -120,14 +125,18 @@ class InstanceSelectorTableViewController: UITableViewController {
         client.run(request) { (response) in
             var snapshot = self.dataSource.snapshot()
             if snapshot.indexOfSection(.selected) != nil {
-                snapshot.deleteItems(snapshot.itemIdentifiers(inSection: .selected))
+                snapshot.deleteSections([.selected])
             }
 
             if case let .success(instance, _) = response {
-                if !snapshot.sectionIdentifiers.contains(.selected) {
+                if snapshot.indexOfSection(.recommendedInstances) != nil {
+                    snapshot.insertSections([.selected], beforeSection: .recommendedInstances)
+                } else {
                     snapshot.appendSections([.selected])
                 }
+                
                 snapshot.appendItems([.selected(url, instance)], toSection: .selected)
+                
                 DispatchQueue.main.async {
                     self.dataSource.apply(snapshot)
                 }
@@ -137,14 +146,47 @@ class InstanceSelectorTableViewController: UITableViewController {
     
     private func loadRecommendedInstances() {
         InstanceSelector.getInstances(category: nil) { (response) in
-            guard case let .success(instances, _) = response else { fatalError() }
-            
-            self.recommendedInstances = instances
-            self.filterRecommendedResults()
+            DispatchQueue.main.async {
+                switch response {
+                case let .failure(error):
+                    self.showRecommendationsError(error)
+                case let .success(instances, _):
+                    self.recommendedInstances = instances
+                    self.filterRecommendedResults()
+                }
+            }
         }
     }
     
-    func filterRecommendedResults() {
+    private func showRecommendationsError(_ error: Client.Error) {
+        let footer = UITableViewHeaderFooterView()
+        footer.translatesAutoresizingMaskIntoConstraints = false
+        
+        let label = UILabel()
+        label.translatesAutoresizingMaskIntoConstraints = false
+        label.textColor = .secondaryLabel
+        label.textAlignment = .center
+        label.font = .boldSystemFont(ofSize: 17)
+        label.numberOfLines = 0
+        label.text = "Could not fetch suggested instances: \(error.localizedDescription)"
+
+        footer.contentView.addSubview(label)
+        
+        NSLayoutConstraint.activate([
+            label.leadingAnchor.constraint(equalToSystemSpacingAfter: footer.contentView.leadingAnchor, multiplier: 1),
+            footer.contentView.trailingAnchor.constraint(equalToSystemSpacingAfter: label.trailingAnchor, multiplier: 1),
+            label.topAnchor.constraint(equalTo: footer.contentView.topAnchor, constant: 8),
+            label.bottomAnchor.constraint(equalTo: footer.contentView.bottomAnchor, constant: 8),
+        ])
+        
+        let fittingSize = CGSize(width: tableView.bounds.width - (tableView.safeAreaInsets.left + tableView.safeAreaInsets.right), height: 0)
+        let size = footer.systemLayoutSizeFitting(fittingSize, withHorizontalFittingPriority: .required, verticalFittingPriority: .fittingSizeLevel)
+        footer.frame = CGRect(origin: .zero, size: size)
+        
+        tableView.tableFooterView = footer
+    }
+    
+    private func filterRecommendedResults() {
         let filteredInstances: [InstanceSelector.Instance]
         if let currentQuery = currentQuery, !currentQuery.isEmpty {
             filteredInstances = recommendedInstances.filter {
@@ -155,12 +197,20 @@ class InstanceSelectorTableViewController: UITableViewController {
         }
 
         var snapshot = self.dataSource.snapshot()
-        snapshot.deleteSections([.recommendedInstances])
-        snapshot.appendSections([.recommendedInstances])
-        snapshot.appendItems(filteredInstances.map { Item.recommended($0) }, toSection: .recommendedInstances)
-        DispatchQueue.main.async {
-            self.dataSource.apply(snapshot)
+        if snapshot.indexOfSection(.recommendedInstances) != nil {
+            let toRemove = snapshot.itemIdentifiers(inSection: .recommendedInstances).filter {
+                if case .recommended(_) = $0 {
+                    return true
+                } else {
+                    return false
+                }
+            }
+            snapshot.deleteItems(toRemove)
+        } else {
+            snapshot.appendSections([.recommendedInstances])
         }
+        snapshot.appendItems(filteredInstances.map { Item.recommended($0) }, toSection: .recommendedInstances)
+        self.dataSource.apply(snapshot)
     }
     
     // MARK: - Table view delegate
@@ -194,29 +244,30 @@ extension InstanceSelectorTableViewController {
         case recommended(InstanceSelector.Instance)
         
         static func ==(lhs: Item, rhs: Item) -> Bool {
-            if case let .selected(url, instance) = lhs,
-                case let .selected(otherUrl, other) = rhs {
-                return url == otherUrl && instance.uri == other.uri
-            } else if case let .recommended(instance) = lhs,
-                case let .recommended(other) = rhs {
-                return instance.domain == other.domain
+            switch (lhs, rhs) {
+            case let (.selected(urlA, instanceA), .selected(urlB, instanceB)):
+                return urlA == urlB && instanceA.uri == instanceB.uri
+            case let (.recommended(a), .recommended(b)):
+                return a.domain == b.domain
+            default:
+                return false
             }
-            return false
         }
         
         func hash(into hasher: inout Hasher) {
             switch self {
             case let .selected(url, instance):
-                hasher.combine(Section.selected)
+                hasher.combine(0)
                 hasher.combine(url)
                 hasher.combine(instance.uri)
             case let .recommended(instance):
-                hasher.combine(Section.recommendedInstances)
+                hasher.combine(1)
                 hasher.combine(instance.domain)
             }
         }
     }
     class DataSource: UITableViewDiffableDataSource<Section, Item> {
+        
     }
 }
 

Tusker/Screens/Timeline/TimelineTableViewController.swift

@@ -20,6 +20,7 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
     private var older: RequestRange?
     
     private var didConfirmLoadMore = false
+    private var isShowingTimelineDescription = false
     
     init(for timeline: Timeline, mastodonController: MastodonController) {
         self.timeline = timeline
@@ -58,6 +59,42 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
         
         tableView.register(UINib(nibName: "TimelineStatusTableViewCell", bundle: .main), forCellReuseIdentifier: "statusCell")
         tableView.register(UINib(nibName: "ConfirmLoadMoreTableViewCell", bundle: .main), forCellReuseIdentifier: "confirmLoadMoreCell")
+        tableView.register(UINib(nibName: "PublicTimelineDescriptionTableViewCell", bundle: .main), forCellReuseIdentifier: "publicTimelineDescriptionCell")
+        
+        if case let .public(local: local) = timeline,
+           (local && !Preferences.shared.hasShownLocalTimelineDescription) || (!local && !Preferences.shared.hasShownFederatedTimelineDescription) {
+            isShowingTimelineDescription = true
+            
+            var snapshot = self.dataSource.snapshot()
+            snapshot.appendSections([.header])
+            snapshot.appendItems([.publicTimelineDescription(local: local)], toSection: .header)
+            self.dataSource.apply(snapshot, animatingDifferences: false)
+        }
+        
+    }
+    
+    override func viewDidAppear(_ animated: Bool) {
+        super.viewDidAppear(animated)
+        
+        if case let .public(local: local) = timeline {
+            if local {
+                Preferences.shared.hasShownLocalTimelineDescription = true
+            } else {
+                Preferences.shared.hasShownFederatedTimelineDescription = true
+            }
+        }
+    }
+    
+    override func viewDidDisappear(_ animated: Bool) {
+        super.viewDidDisappear(animated)
+        
+        if isShowingTimelineDescription {
+            isShowingTimelineDescription = false
+            
+            var snapshot = self.dataSource.snapshot()
+            snapshot.deleteSections([.header])
+            self.dataSource.apply(snapshot, animatingDifferences: false)
+        }
     }
     
     // MARK: - DiffableTimelineLikeTableViewController
@@ -87,6 +124,17 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
                 self.didConfirmLoadMore = false
             }
             return cell
+            
+        case .publicTimelineDescription(local: let local):
+            let cell = tableView.dequeueReusableCell(withIdentifier: "publicTimelineDescriptionCell", for: indexPath) as! PublicTimelineDescriptionTableViewCell
+            cell.mastodonController = mastodonController
+            cell.local = local
+            cell.didDismiss = { [unowned self] in
+                var snapshot = self.dataSource.snapshot()
+                snapshot.deleteSections([.header])
+                self.dataSource.apply(snapshot)
+            }
+            return cell
         }
     }
     
@@ -108,10 +156,13 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
                 self.older = pagination?.older
                 
                 self.mastodonController.persistentContainer.addAll(statuses: statuses) {
-                    var snapshot = Snapshot()
-                    snapshot.appendSections([.statuses, .footer])
-                    snapshot.appendItems(statuses.map { .status(id: $0.id, state: .unknown) }, toSection: .statuses)
-                    completion(.success(snapshot))
+                    DispatchQueue.main.async {
+                        var snapshot = self.dataSource.snapshot()
+                        snapshot.deleteSections([.statuses, .footer])
+                        snapshot.appendSections([.statuses, .footer])
+                        snapshot.appendItems(statuses.map { .status(id: $0.id, state: .unknown) }, toSection: .statuses)
+                        completion(.success(snapshot))
+                    }
                 }
             }
         }
@@ -196,16 +247,33 @@ class TimelineTableViewController: DiffableTimelineLikeTableViewController<Timel
         }
     }
     
+    override func tableView(_ tableView: UITableView, didEndDisplaying cell: UITableViewCell, forRowAt indexPath: IndexPath) {
+        if let item = dataSource.itemIdentifier(for: indexPath),
+           case .publicTimelineDescription(local: _) = item {
+            // trying to remove cells right in didEndDisplaying crashes in UIKit
+            DispatchQueue.main.async {
+                    self.tableView.contentOffset.y -= cell.bounds.height
+                
+                var snapshot = self.dataSource.snapshot()
+                snapshot.deleteItems([item])
+                self.dataSource.apply(snapshot) {
+                }
+            }
+        }
+    }
+    
 }
 
 extension TimelineTableViewController {
     enum Section: Hashable, CaseIterable {
+        case header
         case statuses
         case footer
     }
     enum Item: Hashable {
         case status(id: String, state: StatusState)
         case confirmLoadMore
+        case publicTimelineDescription(local: Bool)
         
         static func ==(lhs: Item, rhs: Item) -> Bool {
             switch (lhs, rhs) {
@@ -213,6 +281,8 @@ extension TimelineTableViewController {
                 return a == b
             case (.confirmLoadMore, .confirmLoadMore):
                 return true
+            case let (.publicTimelineDescription(local: a), .publicTimelineDescription(local: b)):
+                return a == b
             default:
                 return false
             }
@@ -225,6 +295,9 @@ extension TimelineTableViewController {
                 hasher.combine(id)
             case .confirmLoadMore:
                 hasher.combine(1)
+            case let .publicTimelineDescription(local: local):
+                hasher.combine(2)
+                hasher.combine(local)
             }
         }
     }

Tusker/Screens/Utilities/DiffableTimelineLikeTableViewController.swift

@@ -156,8 +156,9 @@ class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable,
         // this assumes that indexPathsForVisibleRows is always in order
         lastLastVisibleRow = tableView.indexPathsForVisibleRows?.last
         
-        let orderedContentSections = dataSource.snapshot().sectionIdentifiers.filter { timelineContentSections().contains($0) }
-        if indexPath.section == orderedContentSections.count - 1,
+        let orderedContentSections = dataSource.snapshot().sectionIdentifiers.enumerated().filter { timelineContentSections().contains($0.element) }
+        if let lastContentSection = orderedContentSections.last,
+           indexPath.section == lastContentSection.offset,
            indexPath.row == tableView.numberOfRows(inSection: indexPath.section) - 1 {
             
             loadOlder()
@@ -187,7 +188,8 @@ class DiffableTimelineLikeTableViewController<Section: Hashable & CaseIterable,
         
         var item: Item? = nil
         for section in timelineContentSections() {
-            if let first = snapshot.itemIdentifiers(inSection: section).first {
+            if snapshot.indexOfSection(section) != nil,
+               let first = snapshot.itemIdentifiers(inSection: section).first {
                 item = first
                 break
             }

Tusker/Screens/Utilities/Previewing.swift

@@ -67,7 +67,9 @@ extension MenuPreviewProvider {
                     guard let self = self,
                           case let .success(results, _) = response,
                           let relationship = results.first else {
-                              elementHandler([])
+                              DispatchQueue.main.async {
+                                  elementHandler([])
+                              }
                               return
                           }
                     let following = relationship.following

Tusker/Views/ContentTextView.swift

@@ -143,9 +143,9 @@ class ContentTextView: LinkTextView {
             case "del":
                 attributed.addAttribute(.strikethroughStyle, value: NSUnderlineStyle.single.rawValue, range: attributed.fullRange)
             case "code":
-                attributed.addAttribute(.font, value: UIFont.monospacedSystemFont(ofSize: self.font!.pointSize, weight: .regular), range: attributed.fullRange)
+                attributed.addAttribute(.font, value: UIFont.monospacedSystemFont(ofSize: defaultFont.pointSize, weight: .regular), range: attributed.fullRange)
             case "pre":
-                attributed.addAttribute(.font, value: UIFont.monospacedSystemFont(ofSize: self.font!.pointSize, weight: .regular), range: attributed.fullRange)
+                attributed.addAttribute(.font, value: UIFont.monospacedSystemFont(ofSize: defaultFont.pointSize, weight: .regular), range: attributed.fullRange)
                 attributed.append(NSAttributedString(string: "\n\n"))
             case "ol", "ul":
                 attributed.trimLeadingCharactersInSet(.whitespacesAndNewlines)
@@ -157,7 +157,7 @@ class ContentTextView: LinkTextView {
                 if parentTag == "ol" {
                     let index = (try? node.elementSiblingIndex()) ?? 0
                     // we use the monospace digit font so that the periods of all the list items line up
-                    bullet = NSAttributedString(string: "\(index + 1).\t", attributes: [.font: UIFont.monospacedDigitSystemFont(ofSize: self.font!.pointSize, weight: .regular)])
+                    bullet = NSAttributedString(string: "\(index + 1).\t", attributes: [.font: UIFont.monospacedDigitSystemFont(ofSize: defaultFont.pointSize, weight: .regular)])
                 } else if parentTag == "ul" {
                     bullet = NSAttributedString(string: "\u{2022}\t")
                 } else {

Tusker/Views/Timeline Description Cell/PublicTimelineDescriptionTableViewCell.swift

@@ -0,0 +1,57 @@
+//
+//  PublicTimelineDescriptionTableViewCell.swift
+//  PublicTimelineDescriptionTableViewCell
+//
+//  Created by Shadowfacts on 8/7/21.
+//  Copyright © 2021 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+class PublicTimelineDescriptionTableViewCell: UITableViewCell {
+    
+    weak var mastodonController: MastodonController!
+    
+    var local = false {
+        didSet {
+            updateLabel()
+        }
+    }
+    var didDismiss: (() -> Void)?
+
+    @IBOutlet private weak var descriptionLabel: UILabel!
+    
+    override func awakeFromNib() {
+        super.awakeFromNib()
+        
+        if #available(iOS 15.0, *) {
+            contentView.backgroundColor = .tintColor
+        } else {
+            contentView.backgroundColor = .systemBlue
+        }
+    }
+    
+    private func updateLabel() {
+        let str = NSMutableAttributedString()
+        let instanceStr = NSAttributedString(string: mastodonController.instanceURL.host!, attributes: [
+            .font: UIFont(descriptor: .preferredFontDescriptor(withTextStyle: .body).withSymbolicTraits(.traitBold)!, size: 0)
+        ])
+        if local {
+            str.append(NSAttributedString(string: "The local timeline shows public posts from only "))
+            str.append(instanceStr)
+            str.append(NSAttributedString(string: "."))
+        } else {
+            str.append(NSAttributedString(string: "The federated timeline shows public posts from all users that "))
+            str.append(instanceStr)
+            str.append(NSAttributedString(string: " knows about."))
+        }
+        descriptionLabel.attributedText = str
+    }
+
+}
+
+extension PublicTimelineDescriptionTableViewCell: SelectableTableViewCell {
+    func didSelectCell() {
+        didDismiss?()
+    }
+}

Tusker/Views/Timeline Description Cell/PublicTimelineDescriptionTableViewCell.xib

@@ -0,0 +1,48 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="19150" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" useSafeAreas="YES" colorMatched="YES">
+    <device id="retina6_1" orientation="portrait" appearance="light"/>
+    <dependencies>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="19134"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="System colors in document resources" minToolsVersion="11.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <objects>
+        <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner"/>
+        <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
+        <tableViewCell contentMode="scaleToFill" selectionStyle="default" indentationWidth="10" rowHeight="78" id="KGk-i7-Jjw" customClass="PublicTimelineDescriptionTableViewCell" customModule="Tusker" customModuleProvider="target">
+            <rect key="frame" x="0.0" y="0.0" width="320" height="78"/>
+            <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
+            <tableViewCellContentView key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" tableViewCell="KGk-i7-Jjw" id="H2p-sc-9uM">
+                <rect key="frame" x="0.0" y="0.0" width="320" height="78"/>
+                <autoresizingMask key="autoresizingMask"/>
+                <subviews>
+                    <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Label" textAlignment="natural" lineBreakMode="tailTruncation" numberOfLines="0" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="N97-CH-58I">
+                        <rect key="frame" x="16" y="8" width="288" height="62"/>
+                        <fontDescription key="fontDescription" type="system" pointSize="17"/>
+                        <color key="textColor" white="1" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+                        <nil key="highlightedColor"/>
+                    </label>
+                </subviews>
+                <color key="backgroundColor" systemColor="systemBlueColor"/>
+                <constraints>
+                    <constraint firstAttribute="bottom" secondItem="N97-CH-58I" secondAttribute="bottom" constant="8" id="2Lg-we-j2c"/>
+                    <constraint firstItem="N97-CH-58I" firstAttribute="top" secondItem="H2p-sc-9uM" secondAttribute="top" constant="8" id="FdS-q9-obT"/>
+                    <constraint firstItem="N97-CH-58I" firstAttribute="trailing" secondItem="H2p-sc-9uM" secondAttribute="trailingMargin" id="KqX-Qy-18G"/>
+                    <constraint firstItem="N97-CH-58I" firstAttribute="leading" secondItem="H2p-sc-9uM" secondAttribute="leadingMargin" id="Pqy-8N-OnX"/>
+                </constraints>
+            </tableViewCellContentView>
+            <viewLayoutGuide key="safeArea" id="njF-e1-oar"/>
+            <connections>
+                <outlet property="descriptionLabel" destination="N97-CH-58I" id="z1W-HD-xy9"/>
+            </connections>
+            <point key="canvasLocation" x="131.8840579710145" y="121.875"/>
+        </tableViewCell>
+    </objects>
+    <resources>
+        <systemColor name="systemBlueColor">
+            <color red="0.0" green="0.47843137254901963" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
+        </systemColor>
+    </resources>
+</document>