Add fast account switching on iPhone

Tusker.xcodeproj/project.pbxproj

@@ -211,6 +211,9 @@
 		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 */; };
 		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 */; };
@@ -556,6 +559,9 @@
 		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>"; };
 		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>"; };
@@ -932,6 +938,7 @@
 				D6F2E960249E772F005846BB /* Crash Reporter */,
 				D641C782213DD7F0004B4513 /* Main */,
 				D641C783213DD7FE004B4513 /* Onboarding */,
+				D6A4DCC92553666600D9DE31 /* Fast Account Switcher */,
 				D641C781213DD7DD004B4513 /* Timeline */,
 				D641C784213DD819004B4513 /* Profile */,
 				D641C785213DD83B004B4513 /* Conversation */,
@@ -1227,6 +1234,16 @@
 			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 +1708,7 @@
 				D6A3BC812321B7E600FD64D5 /* FollowNotificationGroupTableViewCell.xib in Resources */,
 				D667E5E12134937B0057A976 /* TimelineStatusTableViewCell.xib in Resources */,
 				D6F2E966249E8BFD005846BB /* CrashReporterViewController.xib in Resources */,
+				D6A4DCCD2553667800D9DE31 /* FastAccountSwitcherViewController.xib in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1830,7 +1848,9 @@
 				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 */,

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/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/Screens/Fast Account Switcher/FastAccountSwitcherViewController.swift

@@ -0,0 +1,244 @@
+//
+//  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() {
+        lastSelectedAccountViewIndex = nil
+        selectionChangedFeedbackGenerator = nil
+        
+        UIView.animate(withDuration: 0.2, delay: 0, options: .curveEaseInOut) {
+            self.view.alpha = 0
+        } completion: { (_) in
+            self.view.alpha = 1
+            self.view.isHidden = true
+        }
+    }
+    
+    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
+            (view.window!.windowScene!.delegate as! SceneDelegate).activateAccount(account)
+        }
+    }
+    
+    // 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)
+                hide()
+            } 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)
+                hide()
+            }
+            
+        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)
+        }
+        
+        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/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/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":