Account for bidi text in combined display/username label

Tusker/Screens/Main/NewMainTabBarViewController.swift

@@ -454,15 +454,20 @@ extension NewMainTabBarViewController {
 extension NewMainTabBarViewController: UITabBarControllerDelegate {
     func tabBarController(_ tabBarController: UITabBarController, shouldSelectTab tab: UITab) -> Bool {
         if tab.identifier == Tab.compose.rawValue {
-            let currentTab = selectedTab
-            // returning false for shouldSelectTab doesn't prevent the UITabBar from being updated (FB14857254)
-            // returning false and then setting selectedTab=tab and selectedTab=currentTab seems to leave things in a bad state (currentTab's VC is on screen but in the disappeared state)
-            // so return true, and then after the tab bar VC has finished updating, go back to currentTab
-            DispatchQueue.main.async {
-                self.selectedTab = currentTab
+            if #unavailable(iOS 18.1) {
+                let currentTab = selectedTab
+                // returning false for shouldSelectTab doesn't prevent the UITabBar from being updated (FB14857254)
+                // returning false and then setting selectedTab=tab and selectedTab=currentTab seems to leave things in a bad state (currentTab's VC is on screen but in the disappeared state)
+                // so return true, and then after the tab bar VC has finished updating, go back to currentTab
+                DispatchQueue.main.async {
+                    self.selectedTab = currentTab
+                }
+                compose(editing: nil)
+                return true
+            } else {
+                compose(editing: nil)
+                return false
             }
-            compose(editing: nil)
-            return true
         } else if let selectedTab,
                   selectedTab == tab,
                   let nav = selectedViewController as? any NavigationControllerProtocol {

Tusker/Views/AccountDisplayAndUserNameLabel.swift

@@ -30,7 +30,9 @@ class AccountDisplayAndUserNameLabel: EmojiLabel {
     
     private func makeAttributedText(state: State) -> NSAttributedString {
         let s = NSMutableAttributedString()
-        s.append(NSAttributedString(string: state.displayName, attributes: [
+        // U+2068 FIRST-STRONG ISOLATE and U+2069 POP DIRECTIONAL ISOLATE
+        // to prevent bidi text in the display name influencing the username
+        s.append(NSAttributedString(string: "\u{2068}\(state.displayName)\u{2069}", attributes: [
             .font: UIFont(descriptor: baseFont.addingAttributes([
                 .traits: [
                     UIFontDescriptor.TraitKey.weight: UIFont.Weight.semibold.rawValue,