Use tab bar on visionOS

Tusker/Scenes/MainSceneDelegate.swift

@@ -253,10 +253,10 @@ class MainSceneDelegate: UIResponder, UIWindowSceneDelegate, TuskerSceneDelegate
         let mastodonController = window!.windowScene!.session.mastodonController!
         mastodonController.initialize()
         
-        let split = MainSplitViewController(mastodonController: mastodonController)
+        #if os(visionOS)
-        #if !canImport(Duckable)
+        return MainTabBarViewController(mastodonController: mastodonController)
-        return split
         #else
+        let split = MainSplitViewController(mastodonController: mastodonController)
         if UIDevice.current.userInterfaceIdiom == .phone,
            #available(iOS 16.0, *) {
             // TODO: maybe the duckable container should be outside the account switching container

Tusker/Screens/Main/MainTabBarViewController.swift

@@ -15,9 +15,11 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
     
     private var composePlaceholder: UIViewController!
     
+    #if !os(visionOS)
     private var fastAccountSwitcher: FastAccountSwitcherViewController!
     private var fastSwitcherIndicator: FastAccountSwitcherIndicatorView!
     private var fastSwitcherConstraints: [NSLayoutConstraint] = []
+    #endif
     
     var selectedTab: Tab {
         return Tab(rawValue: selectedIndex)!
@@ -60,6 +62,7 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
             embedInNavigationController(Tab.myProfile.createViewController(mastodonController)),
         ]
         
+        #if !os(visionOS)
         fastAccountSwitcher = FastAccountSwitcherViewController()
         fastAccountSwitcher.delegate = self
         fastAccountSwitcher.view.translatesAutoresizingMaskIntoConstraints = false
@@ -74,16 +77,13 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
             fastSwitcherIndicator.translatesAutoresizingMaskIntoConstraints = false
             view.addSubview(fastSwitcherIndicator)
         }
+        #endif
         
         tabBar.isSpringLoaded = true
-        
-        #if os(visionOS)
-        registerForTraitChanges([UITraitHorizontalSizeClass.self]) { (self: Self, previousTraitCollection) in
-            self.repositionFastSwitcherIndicator()
-        }
-        #endif
     }
     
+    // Fast account switcher is not supported on visionOS
+    #if !os(visionOS)
     override func viewDidLayoutSubviews() {
         super.viewDidLayoutSubviews()
         
@@ -93,7 +93,6 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
         repositionFastSwitcherIndicator()
     }
     
-    #if !os(visionOS)
     override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
         super.traitCollectionDidChange(previousTraitCollection)
         
@@ -126,6 +125,7 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
         }
     }
     
+    #if !os(visionOS)
     private func repositionFastSwitcherIndicator() {
         guard let myProfileButton = findMyProfileTabBarButton() else {
             return
@@ -146,6 +146,7 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
         }
         NSLayoutConstraint.activate(fastSwitcherConstraints)
     }
+    #endif
     
     private func findMyProfileTabBarButton() -> UIView? {
         let tabBarButtons = tabBar.subviews.filter { String(describing: type(of: $0)).lowercased().contains("button") }
@@ -157,9 +158,11 @@ class MainTabBarViewController: UITabBarController, UITabBarControllerDelegate {
         return myProfileButton
     }
     
+    #if !os(visionOS)
     @objc private func tabBarTapped(_ recognizer: UITapGestureRecognizer) {
         fastAccountSwitcher.hide()
     }
+    #endif
     
     @objc func handleComposeKeyCommand() {
         compose(editing: nil)
@@ -235,6 +238,7 @@ extension MainTabBarViewController {
     }
 }
 
+#if !os(visionOS)
 extension MainTabBarViewController: FastAccountSwitcherViewControllerDelegate {
     func fastAccountSwitcherAddToViewHierarchy(_ fastAccountSwitcher: FastAccountSwitcherViewController) {
         view.addSubview(fastAccountSwitcher.view)
@@ -256,6 +260,7 @@ extension MainTabBarViewController: FastAccountSwitcherViewControllerDelegate {
         return myProfileButton.bounds.contains(locationInButton)
     }
 }
+#endif
 
 extension MainTabBarViewController: TuskerNavigationDelegate {
     var apiController: MastodonController! { mastodonController }
@@ -357,10 +362,14 @@ extension MainTabBarViewController: BackgroundableViewController {
 
 extension MainTabBarViewController: AccountSwitchableViewController {
     var isFastAccountSwitcherActive: Bool {
+        #if os(visionOS)
+        return false
+        #else
         if let fastAccountSwitcher {
             return !fastAccountSwitcher.view.isHidden
         } else {
             return false
         }
+        #endif
     }
 }