Add account switching animation

Pachyderm/Client.swift

@@ -76,7 +76,6 @@ public class Client {
                 return
             }
             guard let result = try? Client.decoder.decode(Result.self, from: data) else {
-                print(request)
                 completion(.failure(.invalidModel))
                 return
             }

Pachyderm/Model/Emoji.swift

@@ -14,6 +14,25 @@ public class Emoji: Codable {
     public let staticURL: URL
     public let visibleInPicker: Bool
     
+    public required init(from decoder: Decoder) throws {
+        let container = try decoder.container(keyedBy: CodingKeys.self)
+        
+        self.shortcode = try container.decode(String.self, forKey: .shortcode)
+        if let url = try? container.decode(URL.self, forKey: .url) {
+            self.url = url
+        } else {
+            let str = try container.decode(String.self, forKey: .url)
+            self.url = URL(string: str.replacingOccurrences(of: " ", with: "%20"))!
+        }
+        if let url = try? container.decode(URL.self, forKey: .staticURL) {
+            self.staticURL = url
+        } else {
+            let staticStr = try container.decode(String.self, forKey: .staticURL)
+            self.staticURL = URL(string: staticStr.replacingOccurrences(of: " ", with: "%20"))!
+        }
+        self.visibleInPicker = try container.decode(Bool.self, forKey: .visibleInPicker)
+    }
+    
     private enum CodingKeys: String, CodingKey {
         case shortcode
         case url

Tusker.xcodeproj/project.pbxproj

@@ -211,6 +211,10 @@
 		D6A3BC8A2321F79B00FD64D5 /* AccountTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A3BC882321F79B00FD64D5 /* AccountTableViewCell.swift */; };
 		D6A3BC8B2321F79B00FD64D5 /* AccountTableViewCell.xib in Resources */ = {isa = PBXBuildFile; fileRef = D6A3BC892321F79B00FD64D5 /* AccountTableViewCell.xib */; };
 		D6A3BC8F2321FFB900FD64D5 /* StatusActionAccountListTableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A3BC8D2321FFB900FD64D5 /* StatusActionAccountListTableViewController.swift */; };
+		D6A4DCCC2553667800D9DE31 /* FastAccountSwitcherViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A4DCCA2553667800D9DE31 /* FastAccountSwitcherViewController.swift */; };
+		D6A4DCCD2553667800D9DE31 /* FastAccountSwitcherViewController.xib in Resources */ = {isa = PBXBuildFile; fileRef = D6A4DCCB2553667800D9DE31 /* FastAccountSwitcherViewController.xib */; };
+		D6A4DCE525537C7A00D9DE31 /* FastSwitchingAccountView.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A4DCE425537C7A00D9DE31 /* FastSwitchingAccountView.swift */; };
+		D6A57408255C53EC00674551 /* ComposeTextViewCaretScrolling.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A57407255C53EC00674551 /* ComposeTextViewCaretScrolling.swift */; };
 		D6A5BB2B23BAEF61003BF21D /* APIMocks.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A5BB2A23BAEF61003BF21D /* APIMocks.swift */; };
 		D6A5BB2D23BBA9C4003BF21D /* MyProfileTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A5BB2C23BBA9C4003BF21D /* MyProfileTests.swift */; };
 		D6A5BB2F23BBAC97003BF21D /* DelegatingResponse.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6A5BB2E23BBAC97003BF21D /* DelegatingResponse.swift */; };
@@ -293,6 +297,7 @@
 		D6F2E966249E8BFD005846BB /* CrashReporterViewController.xib in Resources */ = {isa = PBXBuildFile; fileRef = D6F2E964249E8BFD005846BB /* CrashReporterViewController.xib */; };
 		D6F953EC212519E700CF0F2B /* TimelineTableViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6F953EB212519E700CF0F2B /* TimelineTableViewController.swift */; };
 		D6F953F021251A2900CF0F2B /* MastodonController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6F953EF21251A2900CF0F2B /* MastodonController.swift */; };
+		D6FF9860255C717400845181 /* AccountSwitchingContainerViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = D6FF985F255C717400845181 /* AccountSwitchingContainerViewController.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -556,6 +561,10 @@
 		D6A3BC882321F79B00FD64D5 /* AccountTableViewCell.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AccountTableViewCell.swift; sourceTree = "<group>"; };
 		D6A3BC892321F79B00FD64D5 /* AccountTableViewCell.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = AccountTableViewCell.xib; sourceTree = "<group>"; };
 		D6A3BC8D2321FFB900FD64D5 /* StatusActionAccountListTableViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StatusActionAccountListTableViewController.swift; sourceTree = "<group>"; };
+		D6A4DCCA2553667800D9DE31 /* FastAccountSwitcherViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FastAccountSwitcherViewController.swift; sourceTree = "<group>"; };
+		D6A4DCCB2553667800D9DE31 /* FastAccountSwitcherViewController.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = FastAccountSwitcherViewController.xib; sourceTree = "<group>"; };
+		D6A4DCE425537C7A00D9DE31 /* FastSwitchingAccountView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FastSwitchingAccountView.swift; sourceTree = "<group>"; };
+		D6A57407255C53EC00674551 /* ComposeTextViewCaretScrolling.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposeTextViewCaretScrolling.swift; sourceTree = "<group>"; };
 		D6A5BB2A23BAEF61003BF21D /* APIMocks.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = APIMocks.swift; sourceTree = "<group>"; };
 		D6A5BB2C23BBA9C4003BF21D /* MyProfileTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MyProfileTests.swift; sourceTree = "<group>"; };
 		D6A5BB2E23BBAC97003BF21D /* DelegatingResponse.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DelegatingResponse.swift; sourceTree = "<group>"; };
@@ -641,6 +650,7 @@
 		D6F2E964249E8BFD005846BB /* CrashReporterViewController.xib */ = {isa = PBXFileReference; lastKnownFileType = file.xib; path = CrashReporterViewController.xib; sourceTree = "<group>"; };
 		D6F953EB212519E700CF0F2B /* TimelineTableViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineTableViewController.swift; sourceTree = "<group>"; };
 		D6F953EF21251A2900CF0F2B /* MastodonController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MastodonController.swift; sourceTree = "<group>"; };
+		D6FF985F255C717400845181 /* AccountSwitchingContainerViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AccountSwitchingContainerViewController.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -932,6 +942,7 @@
 				D6F2E960249E772F005846BB /* Crash Reporter */,
 				D641C782213DD7F0004B4513 /* Main */,
 				D641C783213DD7FE004B4513 /* Onboarding */,
+				D6A4DCC92553666600D9DE31 /* Fast Account Switcher */,
 				D641C781213DD7DD004B4513 /* Timeline */,
 				D641C784213DD819004B4513 /* Profile */,
 				D641C785213DD83B004B4513 /* Conversation */,
@@ -966,6 +977,7 @@
 		D641C782213DD7F0004B4513 /* Main */ = {
 			isa = PBXGroup;
 			children = (
+				D6FF985F255C717400845181 /* AccountSwitchingContainerViewController.swift */,
 				D6F0B12A24A3071C001E48C3 /* MainSplitViewController.swift */,
 				04DACE8B212CB14B009840C4 /* MainTabBarViewController.swift */,
 				D6F0B17424A3A1AA001E48C3 /* MainSidebarViewController.swift */,
@@ -1020,6 +1032,7 @@
 				D677284724ECBCB100C732D3 /* ComposeView.swift */,
 				D677284924ECBDF400C732D3 /* ComposeCurrentAccount.swift */,
 				D677284B24ECBE9100C732D3 /* ComposeAvatarImageView.swift */,
+				D6A57407255C53EC00674551 /* ComposeTextViewCaretScrolling.swift */,
 				D62275A924F1E01C00B82A16 /* ComposeTextView.swift */,
 				D6C99FCA24FADC91005C74D3 /* MainComposeTextView.swift */,
 				D622757324EDF1CD00B82A16 /* ComposeAttachmentsList.swift */,
@@ -1227,6 +1240,16 @@
 			path = "Status Action Account List";
 			sourceTree = "<group>";
 		};
+		D6A4DCC92553666600D9DE31 /* Fast Account Switcher */ = {
+			isa = PBXGroup;
+			children = (
+				D6A4DCCA2553667800D9DE31 /* FastAccountSwitcherViewController.swift */,
+				D6A4DCCB2553667800D9DE31 /* FastAccountSwitcherViewController.xib */,
+				D6A4DCE425537C7A00D9DE31 /* FastSwitchingAccountView.swift */,
+			);
+			path = "Fast Account Switcher";
+			sourceTree = "<group>";
+		};
 		D6A5BB2623BAC88E003BF21D /* Preferences */ = {
 			isa = PBXGroup;
 			children = (
@@ -1691,6 +1714,7 @@
 				D6A3BC812321B7E600FD64D5 /* FollowNotificationGroupTableViewCell.xib in Resources */,
 				D667E5E12134937B0057A976 /* TimelineStatusTableViewCell.xib in Resources */,
 				D6F2E966249E8BFD005846BB /* CrashReporterViewController.xib in Resources */,
+				D6A4DCCD2553667800D9DE31 /* FastAccountSwitcherViewController.xib in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1830,7 +1854,9 @@
 				D6C99FC724FACFAB005C74D3 /* ActivityIndicatorView.swift in Sources */,
 				D6F953F021251A2900CF0F2B /* MastodonController.swift in Sources */,
 				0411610022B442870030A9B7 /* LoadingLargeImageViewController.swift in Sources */,
+				D6A4DCE525537C7A00D9DE31 /* FastSwitchingAccountView.swift in Sources */,
 				D6412B0724B0237700F5412E /* ProfileStatusesViewController.swift in Sources */,
+				D6A4DCCC2553667800D9DE31 /* FastAccountSwitcherViewController.swift in Sources */,
 				D611C2CF232DC61100C86A49 /* HashtagTableViewCell.swift in Sources */,
 				D627944F23A9C99800D38C68 /* EditListAccountsViewController.swift in Sources */,
 				D6945C3423AC6431005C403C /* AddSavedHashtagViewController.swift in Sources */,
@@ -1841,6 +1867,7 @@
 				D60E2F2E244248BF005F8713 /* MastodonCachePersistentStore.swift in Sources */,
 				D620483623D38075008A63EF /* ContentTextView.swift in Sources */,
 				D6F2E965249E8BFD005846BB /* CrashReporterViewController.swift in Sources */,
+				D6A57408255C53EC00674551 /* ComposeTextViewCaretScrolling.swift in Sources */,
 				D6CA6A94249FADE700AD45C1 /* GalleryPlayerViewController.swift in Sources */,
 				D6A3BC802321B7E600FD64D5 /* FollowNotificationGroupTableViewCell.swift in Sources */,
 				D627944D23A9A03D00D38C68 /* ListTimelineViewController.swift in Sources */,
@@ -1947,6 +1974,7 @@
 				D627FF76217E923E00CC0648 /* DraftsManager.swift in Sources */,
 				D64F80E2215875CC00BEF393 /* XCBActionType.swift in Sources */,
 				04586B4322B301470021BD04 /* AppearancePrefsView.swift in Sources */,
+				D6FF9860255C717400845181 /* AccountSwitchingContainerViewController.swift in Sources */,
 				D670F8B62537DC890046588A /* EmojiPickerWrapper.swift in Sources */,
 				D67C57AF21E28EAD00C3118B /* Array+Uniques.swift in Sources */,
 				D6945C3223AC4D36005C403C /* HashtagTimelineViewController.swift in Sources */,

Tusker/Extensions/UIFont+Traits.swift

@@ -10,7 +10,7 @@ import UIKit
 
 extension UIFont {
     
-    func addingTraits(_ traits: UIFontDescriptor.SymbolicTraits, size: CGFloat? = nil) -> UIFont? {
+    func withTraits(_ traits: UIFontDescriptor.SymbolicTraits, size: CGFloat? = nil) -> UIFont? {
         let descriptor = self.fontDescriptor
         guard let newDescriptor = descriptor.withSymbolicTraits([descriptor.symbolicTraits, traits]) else {
             return nil

Tusker/LazilyDecoding.swift

@@ -37,10 +37,10 @@ public struct LazilyDecoding<Enclosing, Value: Codable> {
             } else {
                 guard let data = instance[keyPath: wrapper.keyPath] else { return wrapper.fallback }
                 do {
-                    let value = try decoder.decode(Value.self, from: data)
-                    wrapper.value = value
+                    let value = try decoder.decode(Box<Value>.self, from: data)
+                    wrapper.value = value.value
                     instance[keyPath: storageKeyPath] = wrapper
-                    return value
+                    return value.value
                 } catch {
                     return wrapper.fallback
                 }
@@ -50,7 +50,7 @@ public struct LazilyDecoding<Enclosing, Value: Codable> {
             var wrapper = instance[keyPath: storageKeyPath]
             wrapper.value = newValue
             instance[keyPath: storageKeyPath] = wrapper
-            let newData = try? encoder.encode(newValue)
+            let newData = try! encoder.encode(Box(value: newValue))
             instance[keyPath: wrapper.keyPath] = newData
         }
     }
@@ -62,3 +62,11 @@ extension LazilyDecoding {
         self.init(from: keyPath, fallback: [] as! Value)
     }
 }
+
+extension LazilyDecoding {
+    // PropertyListEncoder only allows top-level types to be dicts or arrays, which breaks encoding nil-able values.
+    // Wrapping everything in a Box ensures that it's always a dict.
+    private struct Box<T: Codable>: Codable {
+        let value: T
+    }
+}

Tusker/LocalData.swift

@@ -87,7 +87,7 @@ class LocalData: ObservableObject {
     }
     
     private let mostRecentAccountKey = "mostRecentAccount"
-    private var mostRecentAccount: String? {
+    private(set) var mostRecentAccountID: String? {
         get {
             return defaults.string(forKey: mostRecentAccountKey)
         }
@@ -131,7 +131,7 @@ class LocalData: ObservableObject {
     func getMostRecentAccount() -> UserAccountInfo? {
         guard onboardingComplete else { return nil }
         let mostRecent: UserAccountInfo?
-        if let id = mostRecentAccount {
+        if let id = mostRecentAccountID {
             mostRecent = accounts.first { $0.id == id }
         } else {
             mostRecent = nil
@@ -140,7 +140,7 @@ class LocalData: ObservableObject {
     }
     
     func setMostRecentAccount(_ account: UserAccountInfo?) {
-        mostRecentAccount = account?.id
+        mostRecentAccountID = account?.id
     }
 
 }

Tusker/SceneDelegate.swift

@@ -130,50 +130,64 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
     func showAppOrOnboardingUI(session: UISceneSession? = nil) {
         let session = session ?? window!.windowScene!.session
         if LocalData.shared.onboardingComplete {
+            let account = LocalData.shared.getMostRecentAccount()!
             if session.mastodonController == nil {
-                let account = LocalData.shared.getMostRecentAccount()!
                 session.mastodonController = MastodonController.getForAccount(account)
             }
             
-            showAppUI()
+            activateAccount(account, animated: false)
         } else {
-            showOnboardingUI()
+            window!.rootViewController = createOnboardingUI()
         }
     }
     
-    func activateAccount(_ account: LocalData.UserAccountInfo) {
+    func activateAccount(_ account: LocalData.UserAccountInfo, animated: Bool) {
+        let oldIndex = LocalData.shared.accounts.firstIndex(where: { $0.id == LocalData.shared.mostRecentAccountID })!
+        let newIndex = LocalData.shared.accounts.firstIndex(of: account)!
+        
         LocalData.shared.setMostRecentAccount(account)
         window!.windowScene!.session.mastodonController = MastodonController.getForAccount(account)
-        showAppUI()
+        
+        let newRoot = createAppUI()
+        if let container = window?.rootViewController as? AccountSwitchingContainerViewController {
+            let direction: AccountSwitchingContainerViewController.AnimationDirection
+            if animated {
+                direction = newIndex > oldIndex ? .upwards : .downwards
+            } else {
+                direction = .none
+            }
+            container.setRoot(newRoot, animating: direction)
+        } else {
+            window!.rootViewController = AccountSwitchingContainerViewController(root: newRoot)
+        }
     }
     
     func logoutCurrent() {
         LocalData.shared.removeAccount(LocalData.shared.getMostRecentAccount()!)
         if LocalData.shared.onboardingComplete {
-            activateAccount(LocalData.shared.accounts.first!)
+            activateAccount(LocalData.shared.accounts.first!, animated: false)
         } else {
-            showOnboardingUI()
+            window!.rootViewController = createOnboardingUI()
         }
     }
 
-    func showAppUI() {
+    func createAppUI() -> TuskerRootViewController {
         let mastodonController = window!.windowScene!.session.mastodonController!
         mastodonController.getOwnAccount()
         mastodonController.getOwnInstance()
         
-        let rootController: UIViewController
-        if #available(iOS 14.0, *) {
-            rootController = MainSplitViewController(mastodonController: mastodonController)
+        if #available(iOS 14.0, *),
+           UIDevice.current.userInterfaceIdiom != .phone {
+            return MainSplitViewController(mastodonController: mastodonController)
         } else {
-            rootController = MainTabBarViewController(mastodonController: mastodonController)
+            return MainTabBarViewController(mastodonController: mastodonController)
         }
-        window!.rootViewController = rootController
     }
     
-    func showOnboardingUI() {
+    func createOnboardingUI() -> UIViewController {
         let onboarding = OnboardingViewController()
         onboarding.onboardingDelegate = self
-        window!.rootViewController = onboarding
+        return onboarding
     }
     
     @objc func themePrefChanged() {
@@ -184,7 +198,7 @@ class SceneDelegate: UIResponder, UIWindowSceneDelegate {
 
 extension SceneDelegate: OnboardingViewControllerDelegate {
     func didFinishOnboarding(account: LocalData.UserAccountInfo) {
-        activateAccount(account)
+        activateAccount(account, animated: false)
     }
 }
 

Tusker/Screens/Compose/ComposeAttachmentsList.swift

@@ -112,6 +112,7 @@ struct ComposeAttachmentsList: View {
         let proxy = UITableView.appearance(whenContainedInInstancesOf: [ComposeHostingController.self])
         // enable drag and drop to reorder on iPhone
         proxy.dragInteractionEnabled = true
+        proxy.isScrollEnabled = false
     }
     
     private func attachmentsChanged(attachments: [CompositionAttachment]) {

Tusker/Screens/Compose/ComposeTextView.swift

@@ -101,9 +101,10 @@ struct WrappedTextView: UIViewRepresentable {
         return Coordinator(text: $text, didChange: textDidChange)
     }
     
-    class Coordinator: NSObject, UITextViewDelegate {
+    class Coordinator: NSObject, UITextViewDelegate, ComposeTextViewCaretScrolling {
         var text: Binding<String>
         var didChange: ((UITextView) -> Void)?
+        var caretScrollPositionAnimator: UIViewPropertyAnimator?
         
         init(text: Binding<String>, didChange: ((UITextView) -> Void)?) {
             self.text = text
@@ -113,6 +114,8 @@ struct WrappedTextView: UIViewRepresentable {
         func textViewDidChange(_ textView: UITextView) {
             text.wrappedValue = textView.text
             didChange?(textView)
+            
+            ensureCursorVisible(textView: textView)
         }
     }
 }

Tusker/Screens/Compose/ComposeTextViewCaretScrolling.swift

@@ -0,0 +1,60 @@
+//
+//  ComposeTextViewCaretScrolling.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 11/11/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+protocol ComposeTextViewCaretScrolling: class {
+    var caretScrollPositionAnimator: UIViewPropertyAnimator? { get set }
+}
+
+extension ComposeTextViewCaretScrolling {
+    func ensureCursorVisible(textView: UITextView) {
+        guard textView.isFirstResponder,
+              let range = textView.selectedTextRange,
+              let scrollView = findParentScrollView(of: textView) else {
+            return
+        }
+        
+        // We use a UIViewProperty animator to change the scroll view position so that we can store the currently
+        // running one on the Coordinator. This allows us to cancel the running one, preventing multiple animations
+        // from attempting to change the scroll view offset simultaneously, causing it to jitter around. This can
+        // happen if the user is pressing return and quickly creating many new lines.
+        
+        if let existing = caretScrollPositionAnimator {
+            existing.stopAnimation(true)
+        }
+        
+        let cursorRect = textView.caretRect(for: range.start)
+        var rectToMakeVisible = textView.convert(cursorRect, to: scrollView)
+        
+        // expand the rect to be three times the cursor height centered on the cursor so that there's
+        // some space between the bottom of the line of text being edited and the top of the keyboard
+        rectToMakeVisible.origin.y -= cursorRect.height
+        rectToMakeVisible.size.height *= 3
+        
+        let animator = UIViewPropertyAnimator(duration: 0.1, curve: .linear) {
+            scrollView.scrollRectToVisible(rectToMakeVisible, animated: false)
+        }
+        self.caretScrollPositionAnimator = animator
+        animator.startAnimation()
+    }
+    
+    private func findParentScrollView(of view: UIView) -> UIScrollView? {
+        var current: UIView = view
+        while let superview = current.superview {
+            if let scrollView = superview as? UIScrollView,
+               scrollView.isScrollEnabled {
+                return scrollView
+            } else {
+                current = superview
+            }
+        }
+        
+        return nil
+    }
+}

Tusker/Screens/Compose/MainComposeTextView.swift

@@ -171,12 +171,12 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
         return Coordinator(text: $text, uiState: uiState, didChange: textDidChange)
     }
     
-    class Coordinator: NSObject, UITextViewDelegate, ComposeAutocompleteHandler {
+    class Coordinator: NSObject, UITextViewDelegate, ComposeAutocompleteHandler, ComposeTextViewCaretScrolling {
         weak var textView: UITextView?
         var text: Binding<String>
         var didChange: (UITextView) -> Void
         var uiState: ComposeUIState
-        private var caretScrollPositionAnimator: UIViewPropertyAnimator?
+        var caretScrollPositionAnimator: UIViewPropertyAnimator?
         
         init(text: Binding<String>, uiState: ComposeUIState, didChange: @escaping (UITextView) -> Void) {
             self.text = text
@@ -188,53 +188,7 @@ struct MainComposeWrappedTextView: UIViewRepresentable {
             text.wrappedValue = textView.text
             didChange(textView)
             
-            ensureCursorVisible()
-        }
-        
-        private func ensureCursorVisible() {
-            guard let textView = textView,
-                  textView.isFirstResponder,
-                  let range = textView.selectedTextRange,
-                  let scrollView = findParentScrollView() else {
-                return
-            }
-            
-            // We use a UIViewProperty animator to change the scroll view position so that we can store the currently
-            // running one on the Coordinator. This allows us to cancel the running one, preventing multiple animations
-            // from attempting to change the scroll view offset simultaneously, causing it to jitter around. This can
-            // happen if the user is pressing return and quickly creating many new lines.
-            
-            if let existing = caretScrollPositionAnimator {
-                existing.stopAnimation(true)
-            }
-            
-            let cursorRect = textView.caretRect(for: range.start)
-            var rectToMakeVisible = textView.convert(cursorRect, to: scrollView)
-            
-            // move Y position of the rect that will be made visible down by the cursor's height so that there's
-            // some space between the bottom of the line of text being edited and the top of the keyboard
-            rectToMakeVisible.origin.y += cursorRect.height
-            
-            let animator = UIViewPropertyAnimator(duration: 0.1, curve: .linear) {
-                scrollView.scrollRectToVisible(rectToMakeVisible, animated: false)
-            }
-            self.caretScrollPositionAnimator = animator
-            animator.startAnimation()
-        }
-        
-        private func findParentScrollView() -> UIScrollView? {
-            guard let textView = textView else { return nil }
-            
-            var current: UIView = textView
-            while let superview = current.superview {
-                if let scrollView = superview as? UIScrollView {
-                    return scrollView
-                } else {
-                    current = superview
-                }
-            }
-            
-            return nil
+            ensureCursorVisible(textView: textView)
         }
         
         @objc func formatButtonPressed(_ sender: UIBarButtonItem) {

Tusker/Screens/Fast Account Switcher/FastAccountSwitcherViewController.swift

@@ -0,0 +1,248 @@
+//
+//  FastAccountSwitcherViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 11/4/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+protocol FastAccountSwitcherViewControllerDelegate: class {
+    func fastAccountSwitcher(_ fastAccountSwitcher: FastAccountSwitcherViewController, triggerZoneContains point: CGPoint) -> Bool
+}
+
+class FastAccountSwitcherViewController: UIViewController {
+    
+    weak var delegate: FastAccountSwitcherViewControllerDelegate?
+    
+    @IBOutlet weak var dimmingView: UIView!
+    @IBOutlet weak var blurContentView: UIView!
+    @IBOutlet weak var accountsStack: UIStackView!
+    
+    private var accountViews: [FastSwitchingAccountView] = []
+    private var lastSelectedAccountViewIndex: Int?
+    private var selectionChangedFeedbackGenerator: UIImpactFeedbackGenerator?
+    private var touchBeganFeedbackWorkItem: DispatchWorkItem?
+    
+    init() {
+        super.init(nibName: "FastAccountSwitcherViewController", bundle: .main)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        view.isHidden = true
+        
+        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleTap(_:))))
+        accountsStack.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: #selector(handlePan(_:))))
+    }
+    
+    func createSwitcherGesture() -> UIGestureRecognizer {
+        let recognizer = UILongPressGestureRecognizer(target: self, action: #selector(handleLongPress(_:)))
+        recognizer.delegate = self
+        recognizer.minimumPressDuration = 0.25
+        return recognizer
+    }
+    
+    func show() {
+        createAccountViews()
+        
+        view.isHidden = false
+        
+        if UIAccessibility.prefersCrossFadeTransitionsBackwardsCompat {
+            view.alpha = 0
+            UIView.animate(withDuration: 0.2, delay: 0, options: [.curveEaseInOut, .allowUserInteraction]) {
+                self.view.alpha = 1
+            }
+        } else {
+            let totalDuration: TimeInterval = 0.5
+            UIView.animateKeyframes(withDuration: totalDuration, delay: 0, options: .allowUserInteraction) {
+                self.view.alpha = 0
+                UIView.addKeyframe(withRelativeStartTime: 0, relativeDuration: 0.5) {
+                    self.view.alpha = 1
+                }
+                
+                for (index, accountView) in self.accountViews.reversed().enumerated() {
+                    let relStart = 0.5 * Double(index) / Double(self.accountsStack.arrangedSubviews.count)
+                    let relDuration = 0.5 * 2 / Double(self.accountsStack.arrangedSubviews.count)
+                    
+                    accountView.alpha = 0
+                    accountView.transform = CGAffineTransform(scaleX: 1.2, y: 1.2)
+                    UIView.addKeyframe(withRelativeStartTime: relStart, relativeDuration: relDuration) {
+                        accountView.alpha = 1
+                        accountView.transform = CGAffineTransform(scaleX: 0.9, y: 0.9)
+                    }
+                    
+                    UIView.addKeyframe(withRelativeStartTime: relStart + relDuration, relativeDuration: relDuration) {
+                        accountView.transform = .identity
+                    }
+                }
+            }
+        }
+    }
+    
+    func hide(completion: (() -> Void)? = nil) {
+        lastSelectedAccountViewIndex = nil
+        selectionChangedFeedbackGenerator = nil
+        
+        UIView.animate(withDuration: 0.15, delay: 0, options: .curveEaseInOut) {
+            self.view.alpha = 0
+        } completion: { (_) in
+            self.view.alpha = 1
+            self.view.isHidden = true
+            completion?()
+        }
+    }
+    
+    private func createAccountViews() {
+        accountsStack.arrangedSubviews.forEach { $0.removeFromSuperview() }
+        accountViews = []
+        
+        for account in LocalData.shared.accounts {
+            let accountView = FastSwitchingAccountView(account: account)
+            accountView.isCurrent = account.id == LocalData.shared.mostRecentAccountID
+            accountsStack.addArrangedSubview(accountView)
+            accountViews.append(accountView)
+        }
+    }
+    
+    private func accountViewIndex(at point: CGPoint) -> Int? {
+        for (index, accountView) in accountViews.enumerated() {
+            let pointInAccountView = accountView.convert(point, from: view)
+            if accountView.bounds.contains(pointInAccountView) {
+                return index
+            }
+        }
+        return nil
+    }
+    
+    private func switchAccount(newIndex: Int, hapticFeedback: Bool = true) {
+        let account = LocalData.shared.accounts[newIndex]
+        
+        if account.id != LocalData.shared.mostRecentAccountID {
+            if hapticFeedback {
+                selectionChangedFeedbackGenerator?.impactOccurred()
+            }
+            selectionChangedFeedbackGenerator = nil
+            
+            hide() {
+                (self.view.window!.windowScene!.delegate as! SceneDelegate).activateAccount(account, animated: true)
+            }
+        } else {
+            hide()
+        }
+    }
+    
+    // MARK: - Interaction
+    
+    @objc private func handleLongPress(_ recognizer: UIGestureRecognizer) {
+        switch recognizer.state {
+        case .began:
+            selectionChangedFeedbackGenerator = UIImpactFeedbackGenerator(style: .medium)
+            selectionChangedFeedbackGenerator?.impactOccurred()
+            selectionChangedFeedbackGenerator?.prepare()
+            
+            show()
+            
+        case .changed:
+            let location = recognizer.location(in: view)
+            
+            handleGestureMoved(to: location)
+            
+        case .ended:
+            let location = recognizer.location(in: view)
+            if let index = lastSelectedAccountViewIndex {
+                switchAccount(newIndex: index)
+            } else if !(delegate?.fastAccountSwitcher(self, triggerZoneContains: location) ?? false) {
+                hide()
+            }
+            
+        default:
+            break
+        }
+    }
+    
+    @objc private func handlePan(_ recognizer: UIPanGestureRecognizer) {
+        switch recognizer.state {
+        case .changed:
+            let location = recognizer.location(in: view)
+            
+            handleGestureMoved(to: location)
+            
+        case .ended:
+            if let index = lastSelectedAccountViewIndex {
+                switchAccount(newIndex: index)
+            }
+            
+        default:
+            break
+        }
+    }
+    
+    private func handleGestureMoved(to location: CGPoint, hapticFeedback: Bool = true) {
+        let selectedAccountViewIndex = accountViewIndex(at: location)
+        
+        if selectedAccountViewIndex != lastSelectedAccountViewIndex {
+            if let lastSelected = lastSelectedAccountViewIndex {
+                accountViews[lastSelected].isSelected = false
+            }
+            if let newSelected = selectedAccountViewIndex {
+                accountViews[newSelected].isSelected = true
+            }
+            lastSelectedAccountViewIndex = selectedAccountViewIndex
+            
+            if hapticFeedback {
+                selectionChangedFeedbackGenerator?.impactOccurred(intensity: 0.5)
+                selectionChangedFeedbackGenerator?.prepare()
+            }
+        }
+    }
+    
+    @objc private func handleTap(_ recognizer: UITapGestureRecognizer) {
+        if let tappedIndex = accountViewIndex(at: recognizer.location(in: view)) {
+            // cancel the selection-changed feedback initiated in touchesBegan so that,
+            // upon switching, we don't trigger a double feedback
+            touchBeganFeedbackWorkItem?.cancel()
+            touchBeganFeedbackWorkItem = nil
+            
+            switchAccount(newIndex: tappedIndex)
+        } else {
+            hide()
+        }
+    }
+    
+    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
+        if touches.count == 1,
+           let touch = touches.first,
+           accountsStack.bounds.contains(touch.location(in: accountsStack)) {
+            handleGestureMoved(to: touch.location(in: view), hapticFeedback: false)
+            
+            // don't trigger the haptic feedback immedaitely
+            // if the user is merely tapping, not initiating a pan, we don't want to trigger a double-impact
+            // if the tap ends very quickly, this will be cancelled
+            touchBeganFeedbackWorkItem = DispatchWorkItem {
+                self.selectionChangedFeedbackGenerator?.impactOccurred(intensity: 0.5)
+                self.selectionChangedFeedbackGenerator?.prepare()
+                self.touchBeganFeedbackWorkItem = nil
+            }
+            // 100ms determined experimentally to be fast enough that there's not a hugely-perceivable delay when beginning a pan gesture
+            // and slow enough that it's longer than most reasonable-speed taps
+            DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(100), execute: touchBeganFeedbackWorkItem!)
+        }
+        
+        super.touchesBegan(touches, with: event)
+    }
+
+}
+
+extension FastAccountSwitcherViewController: UIGestureRecognizerDelegate {
+    func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
+        let point = gestureRecognizer.location(in: view)
+        return delegate?.fastAccountSwitcher(self, triggerZoneContains: point) ?? false
+    }
+}

Tusker/Screens/Fast Account Switcher/FastAccountSwitcherViewController.xib

@@ -0,0 +1,68 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="17506" 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="17504.1"/>
+        <capability name="Safe area layout guides" minToolsVersion="9.0"/>
+        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
+    </dependencies>
+    <objects>
+        <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner" customClass="FastAccountSwitcherViewController" customModule="Tusker" customModuleProvider="target">
+            <connections>
+                <outlet property="accountsStack" destination="lYU-Bb-3Wi" id="Dxs-ta-ORu"/>
+                <outlet property="blurContentView" destination="1Gd-Da-Vab" id="JqT-uq-1o2"/>
+                <outlet property="dimmingView" destination="Lul-oI-bZ7" id="JhP-ZX-8fb"/>
+                <outlet property="view" destination="i5M-Pr-FkT" id="sfx-zR-JGt"/>
+            </connections>
+        </placeholder>
+        <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
+        <view clearsContextBeforeDrawing="NO" contentMode="scaleToFill" id="i5M-Pr-FkT">
+            <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+            <subviews>
+                <view alpha="0.25" contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="Lul-oI-bZ7">
+                    <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                    <color key="backgroundColor" white="0.0" alpha="1" colorSpace="custom" customColorSpace="genericGamma22GrayColorSpace"/>
+                </view>
+                <visualEffectView opaque="NO" contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="5fd-Ni-Owc">
+                    <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                    <view key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" insetsLayoutMarginsFromSafeArea="NO" id="1Gd-Da-Vab">
+                        <rect key="frame" x="0.0" y="0.0" width="414" height="896"/>
+                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <subviews>
+                            <stackView opaque="NO" contentMode="scaleToFill" axis="vertical" alignment="bottom" translatesAutoresizingMaskIntoConstraints="NO" id="lYU-Bb-3Wi">
+                                <rect key="frame" x="8" y="8" width="398" height="880"/>
+                            </stackView>
+                        </subviews>
+                        <constraints>
+                            <constraint firstItem="lYU-Bb-3Wi" firstAttribute="top" secondItem="1Gd-Da-Vab" secondAttribute="topMargin" placeholder="YES" id="KQs-d5-U3f"/>
+                            <constraint firstAttribute="trailing" secondItem="lYU-Bb-3Wi" secondAttribute="trailingMargin" constant="8" id="UZh-xR-XVt"/>
+                            <constraint firstAttribute="bottomMargin" secondItem="lYU-Bb-3Wi" secondAttribute="bottom" id="j6f-r5-NNI"/>
+                            <constraint firstItem="lYU-Bb-3Wi" firstAttribute="leading" secondItem="1Gd-Da-Vab" secondAttribute="leading" constant="8" id="sae-ga-MGE"/>
+                        </constraints>
+                    </view>
+                    <blurEffect style="systemThinMaterialDark"/>
+                </visualEffectView>
+            </subviews>
+            <viewLayoutGuide key="safeArea" id="fnl-2z-Ty3"/>
+            <gestureRecognizers/>
+            <constraints>
+                <constraint firstAttribute="trailing" secondItem="Lul-oI-bZ7" secondAttribute="trailing" id="9Fp-IG-O9W"/>
+                <constraint firstAttribute="trailing" secondItem="5fd-Ni-Owc" secondAttribute="trailing" id="c27-P9-lLK"/>
+                <constraint firstAttribute="bottom" secondItem="Lul-oI-bZ7" secondAttribute="bottom" id="o6y-tG-MwH"/>
+                <constraint firstItem="5fd-Ni-Owc" firstAttribute="leading" secondItem="i5M-Pr-FkT" secondAttribute="leading" id="phf-PC-bdH"/>
+                <constraint firstItem="5fd-Ni-Owc" firstAttribute="top" secondItem="i5M-Pr-FkT" secondAttribute="top" id="rz7-cQ-PIC"/>
+                <constraint firstAttribute="bottom" secondItem="5fd-Ni-Owc" secondAttribute="bottom" id="sHl-iD-kGi"/>
+                <constraint firstItem="Lul-oI-bZ7" firstAttribute="leading" secondItem="i5M-Pr-FkT" secondAttribute="leading" id="tfE-Xr-YBo"/>
+                <constraint firstItem="Lul-oI-bZ7" firstAttribute="top" secondItem="i5M-Pr-FkT" secondAttribute="top" id="ua7-DO-kdp"/>
+            </constraints>
+            <variation key="default">
+                <mask key="subviews">
+                    <exclude reference="Lul-oI-bZ7"/>
+                </mask>
+            </variation>
+            <point key="canvasLocation" x="140.57971014492756" y="144.64285714285714"/>
+        </view>
+    </objects>
+</document>

Tusker/Screens/Fast Account Switcher/FastSwitchingAccountView.swift

@@ -0,0 +1,116 @@
+//
+//  FastSwitchingAccountView.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 11/4/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+class FastSwitchingAccountView: UIView {
+    
+    let account: LocalData.UserAccountInfo
+    
+    private static let selectedColor = UIColor { (traits) in
+        if traits.userInterfaceStyle == .dark {
+            return UIColor(hue: 211 / 360, saturation: 85 / 100, brightness: 100 / 100, alpha: 1)
+        } else {
+            return UIColor(hue: 211 / 360, saturation: 70 / 100, brightness: 100 / 100, alpha: 1)
+        }
+    }
+    private static let currentColor = UIColor { (traits) in
+        if traits.userInterfaceStyle == .dark {
+            return UIColor(hue: 211 / 360, saturation: 85 / 100, brightness: 85 / 100, alpha: 1)
+        } else {
+            return UIColor(hue: 211 / 360, saturation: 50 / 100, brightness: 100 / 100, alpha: 1)
+        }
+    }
+    var isSelected = false {
+        didSet {
+            updateLabelColors()
+        }
+    }
+    var isCurrent = false {
+        didSet {
+            updateLabelColors()
+        }
+    }
+    
+    private let usernameLabel = UILabel()
+    private let instanceLabel = UILabel()
+    
+    private var avatarRequest: ImageCache.Request?
+    
+    init(account: LocalData.UserAccountInfo) {
+        self.account = account
+        
+        super.init(frame: .zero)
+        
+        usernameLabel.textColor = .white
+        usernameLabel.font = UIFont(descriptor: .preferredFontDescriptor(withTextStyle: .headline), size: 0)
+        usernameLabel.text = account.username
+        
+        instanceLabel.textColor = .white
+        instanceLabel.font = UIFont(descriptor: .preferredFontDescriptor(withTextStyle: .subheadline), size: 0)
+        instanceLabel.text = account.instanceURL.host!
+        
+        let stackView = UIStackView(arrangedSubviews: [
+            usernameLabel,
+            instanceLabel
+        ])
+        stackView.translatesAutoresizingMaskIntoConstraints = false
+        stackView.axis = .vertical
+        stackView.alignment = .trailing
+        addSubview(stackView)
+        
+        let avatarImageView = UIImageView()
+        avatarImageView.translatesAutoresizingMaskIntoConstraints = false
+        avatarImageView.layer.masksToBounds = true
+        avatarImageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 40
+        avatarImageView.image = UIImage(systemName: Preferences.shared.avatarStyle == .circle ? "person.crop.circle" : "person.crop.square")
+        avatarImageView.contentMode = .scaleAspectFit
+        addSubview(avatarImageView)
+        
+        NSLayoutConstraint.activate([
+            avatarImageView.topAnchor.constraint(equalTo: topAnchor, constant: 8),
+            avatarImageView.bottomAnchor.constraint(equalTo: bottomAnchor, constant: -8),
+            avatarImageView.trailingAnchor.constraint(equalTo: trailingAnchor),
+            avatarImageView.widthAnchor.constraint(equalToConstant: 40),
+            avatarImageView.heightAnchor.constraint(equalTo: avatarImageView.widthAnchor),
+            
+            stackView.leadingAnchor.constraint(equalTo: leadingAnchor, constant: 8),
+            stackView.trailingAnchor.constraint(equalTo: avatarImageView.leadingAnchor, constant: -8),
+            stackView.centerYAnchor.constraint(equalTo: avatarImageView.centerYAnchor),
+        ])
+        
+        let controller = MastodonController.getForAccount(account)
+        controller.getOwnAccount { [weak self] (result) in
+            guard let self = self, case let .success(account) = result else { return }
+            self.avatarRequest = ImageCache.avatars.get(account.avatar) { [weak avatarImageView] (data) in
+                guard let avatarImageView = avatarImageView, let data = data, let image = UIImage(data: data) else { return }
+                DispatchQueue.main.async {
+                    avatarImageView.image = image
+                }
+            }
+        }
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    private func updateLabelColors() {
+        let color: UIColor
+        if isSelected {
+            color = FastSwitchingAccountView.selectedColor
+        } else if isCurrent {
+            color = FastSwitchingAccountView.currentColor
+        } else {
+            color = .white
+        }
+        usernameLabel.textColor = color
+        instanceLabel.textColor = color
+    }
+
+}

Tusker/Screens/Main/AccountSwitchingContainerViewController.swift

@@ -0,0 +1,84 @@
+//
+//  AccountSwitchingContainerViewController.swift
+//  Tusker
+//
+//  Created by Shadowfacts on 11/11/20.
+//  Copyright © 2020 Shadowfacts. All rights reserved.
+//
+
+import UIKit
+
+class AccountSwitchingContainerViewController: UIViewController {
+
+    private(set) var root: TuskerRootViewController
+    
+    init(root: TuskerRootViewController) {
+        self.root = root
+        
+        super.init(nibName: nil, bundle: nil)
+    }
+    
+    required init?(coder: NSCoder) {
+        fatalError("init(coder:) has not been implemented")
+    }
+    
+    override func viewDidLoad() {
+        super.viewDidLoad()
+
+        embedChild(root)
+    }
+    
+    func setRoot(_ newRoot: TuskerRootViewController, animating direction: AnimationDirection) {
+        let oldRoot = self.root
+        if direction == .none {
+            oldRoot.removeViewAndController()
+        }
+        self.root = newRoot
+        embedChild(newRoot)
+        
+        if direction != .none {
+            if UIAccessibility.prefersCrossFadeTransitionsBackwardsCompat {
+                newRoot.view.alpha = 0
+                
+                UIView.animate(withDuration: 0.4, delay: 0, options: .curveEaseInOut) {
+                    newRoot.view.alpha = 1
+                    oldRoot.view.alpha = 0
+                } completion: { (_) in
+                    oldRoot.removeViewAndController()
+                }
+            } else {
+                let sign: CGFloat = direction == .downwards ? -1 : 1
+                let newInitialOffset = sign * view.bounds.height
+                
+                newRoot.view.transform = CGAffineTransform(translationX: 0, y: newInitialOffset)
+                
+                UIView.animate(withDuration: 0.3, delay: 0, options: .curveEaseInOut) {
+                    newRoot.view.transform = .identity
+                    oldRoot.view.transform = CGAffineTransform(translationX: 0, y: -newInitialOffset)
+                } completion: { (_) in
+                    oldRoot.removeViewAndController()
+                }
+            }
+        }
+    }
+}
+
+extension AccountSwitchingContainerViewController {
+    enum AnimationDirection {
+        case none, downwards, upwards
+    }
+}
+
+extension AccountSwitchingContainerViewController: TuskerRootViewController {
+    func presentCompose() {
+        root.presentCompose()
+    }
+    
+    func select(tab: MainTabBarViewController.Tab) {
+        root.select(tab: tab)
+    }
+    
+    func getTabController(tab: MainTabBarViewController.Tab) -> UIViewController? {
+        root.getTabController(tab: tab)
+    }
+}

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -14,6 +14,7 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
     weak var mastodonController: MastodonController!
     
     private var composePlaceholder: UIViewController!
+    private var fastAccountSwitcher: FastAccountSwitcherViewController!
     
     var selectedTab: Tab {
         return Tab(rawValue: selectedIndex)!
@@ -53,6 +54,26 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
             embedInNavigationController(Tab.explore.createViewController(mastodonController)),
             embedInNavigationController(Tab.myProfile.createViewController(mastodonController)),
         ]
+        
+        fastAccountSwitcher = FastAccountSwitcherViewController()
+        fastAccountSwitcher.delegate = self
+        fastAccountSwitcher.view.translatesAutoresizingMaskIntoConstraints = false
+        view.addSubview(fastAccountSwitcher.view)
+        NSLayoutConstraint.activate([
+            fastAccountSwitcher.view.leadingAnchor.constraint(equalTo: view.leadingAnchor),
+            fastAccountSwitcher.view.trailingAnchor.constraint(equalTo: view.trailingAnchor),
+            fastAccountSwitcher.view.topAnchor.constraint(equalTo: view.topAnchor),
+            fastAccountSwitcher.view.bottomAnchor.constraint(equalTo: tabBar.topAnchor),
+        ])
+        
+        tabBar.addGestureRecognizer(fastAccountSwitcher.createSwitcherGesture())
+        let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(tabBarTapped))
+        tapRecognizer.cancelsTouchesInView = false
+        tabBar.addGestureRecognizer(tapRecognizer)
+    }
+    
+    @objc private func tabBarTapped(_ recognizer: UITapGestureRecognizer) {
+        fastAccountSwitcher.hide()
     }
     
     func embedInNavigationController(_ vc: UIViewController) -> UINavigationController {
@@ -120,6 +141,20 @@ extension MainTabBarViewController {
     }
 }
 
+extension MainTabBarViewController: FastAccountSwitcherViewControllerDelegate {
+    func fastAccountSwitcher(_ fastAccountSwitcher: FastAccountSwitcherViewController, triggerZoneContains point: CGPoint) -> Bool {
+        let tabBarButtons = tabBar.subviews.filter { String(describing: type(of: $0)).lowercased().contains("button") }
+        // sanity check that there is 1 button per VC
+        guard tabBarButtons.count == viewControllers!.count,
+              let myProfileButton = tabBarButtons.last else {
+            return false
+        }
+        
+        let locationInButton = myProfileButton.convert(point, from: fastAccountSwitcher.view)
+        return myProfileButton.bounds.contains(locationInButton)
+    }
+}
+
 extension MainTabBarViewController: TuskerRootViewController {
     func presentCompose() {
         let vc = ComposeHostingController(mastodonController: mastodonController)

Tusker/Screens/Preferences/PreferencesNavigationController.swift

@@ -69,7 +69,7 @@ class PreferencesNavigationController: UINavigationController {
         let account = notification.userInfo!["account"] as! LocalData.UserAccountInfo
         isSwitchingAccounts = true
         dismiss(animated: true) { // dismiss preferences
-            sceneDelegate.activateAccount(account)
+            sceneDelegate.activateAccount(account, animated: true)
         }
     }
     
@@ -93,7 +93,7 @@ extension PreferencesNavigationController: OnboardingViewControllerDelegate {
             let sceneDelegate = self.view.window!.windowScene!.delegate as! SceneDelegate
             self.dismiss(animated: true) { // dismiss instance selector
                 self.dismiss(animated: true) { // dismiss preferences
-                    sceneDelegate.activateAccount(account)
+                    sceneDelegate.activateAccount(account, animated: false)
                 }
             }
         }

Tusker/Views/ContentTextView.swift

@@ -137,10 +137,10 @@ class ContentTextView: LinkTextView {
                 attributed.append(NSAttributedString(string: "\n\n"))
             case "em", "i":
                 let currentFont: UIFont = attributed.attribute(.font, at: 0, effectiveRange: nil) as? UIFont ?? self.font!
-                attributed.addAttribute(.font, value: currentFont.addingTraits(.traitItalic)!, range: attributed.fullRange)
+                attributed.addAttribute(.font, value: currentFont.withTraits(.traitItalic)!, range: attributed.fullRange)
             case "strong", "b":
                 let currentFont: UIFont = attributed.attribute(.font, at: 0, effectiveRange: nil) as? UIFont ?? self.font!
-                attributed.addAttribute(.font, value: currentFont.addingTraits(.traitBold)!, range: attributed.fullRange)
+                attributed.addAttribute(.font, value: currentFont.withTraits(.traitBold)!, range: attributed.fullRange)
             case "del":
                 attributed.addAttribute(.strikethroughStyle, value: NSUnderlineStyle.single.rawValue, range: attributed.fullRange)
             case "code":