Fixed an issue where theme changes stopped updating nav styling

Session/Conversations/ConversationVC.swift

@@ -497,6 +497,9 @@ final class ConversationVC: BaseVC, SessionUtilRespondingViewController, Convers
         
         startObservingChanges()
         
+        /// If the view is removed and readded to the view hierarchy then `viewWillDisappear` will be called but `viewDidDisappear`
+        /// **won't**, as a result `viewIsDisappearing` would never get set to `false` - do so here to handle this case
+        viewIsDisappearing = false
         viewIsAppearing = true
     }
 

SessionUIKit/Components/TopBannerController.swift

@@ -95,11 +95,7 @@ public class TopBannerController: UIViewController {
         view.addSubview(contentStackView)
         
         contentStackView.addArrangedSubview(bannerContainer)
-        
-        child.willMove(toParent: self)
-        addChild(child)
-        contentStackView.addArrangedSubview(child.view)
-        child.didMove(toParent: self)
+        attachChild()
         
         bannerContainer.addSubview(bannerLabel)
         bannerContainer.addSubview(closeButton)
@@ -155,6 +151,13 @@ public class TopBannerController: UIViewController {
     
     // MARK: - Functions
     
+    public func attachChild() {
+        child.willMove(toParent: self)
+        addChild(child)
+        contentStackView.addArrangedSubview(child.view)
+        child.didMove(toParent: self)
+    }
+    
     public static func show(warning: Warning, inWindowFor view: UIView? = nil) {
         guard Thread.isMainThread else {
             DispatchQueue.main.async {

SessionUIKit/Style Guide/ThemeManager.swift

@@ -1,4 +1,6 @@
 // Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.
+//
+// stringlint:disable
 
 import UIKit
 import GRDB
@@ -203,7 +205,7 @@ public enum ThemeManager {
         func updateIfNeeded(viewController: UIViewController?) {
             guard let viewController: UIViewController = viewController else { return }
             guard
-                let navController: UINavigationController = ((viewController as? UINavigationController) ?? viewController.navigationController),
+                let navController: UINavigationController = retrieveNavigationController(from: viewController),
                 let superview: UIView = navController.view.superview,
                 !navController.isNavigationBarHidden
             else {
@@ -218,9 +220,19 @@ public enum ThemeManager {
             applyNavigationStylingIfNeeded(to: viewController)
             
             // Re-attach to the UI
-            navController.view.removeFromSuperview()
-            superview.addSubview(navController.view)
+            let wasFirstResponder: Bool = (navController.topViewController?.isFirstResponder == true)
+            
+            switch navController.parent {
+                case let topBannerController as TopBannerController:
+                    navController.view.removeFromSuperview()
+                    topBannerController.attachChild()
+                    
+                default:
+                    navController.view.removeFromSuperview()
+                    superview.addSubview(navController.view)
+            }
             navController.topViewController?.setNeedsStatusBarAppearanceUpdate()
+            if wasFirstResponder { navController.topViewController?.becomeFirstResponder() }
             
             // Recurse through the rest of the UI
             updateIfNeeded(viewController:
@@ -263,6 +275,16 @@ public enum ThemeManager {
         }
     }
     
+    private static func retrieveNavigationController(from viewController: UIViewController) -> UINavigationController? {
+        switch viewController {
+            case let navController as UINavigationController: return navController
+            case let topBannerController as TopBannerController:
+                return (topBannerController.children.first as? UINavigationController)
+                
+            default: return viewController.navigationController
+        }
+    }
+    
     public static func applyWindowStyling() {
         guard Thread.isMainThread else {
             return DispatchQueue.main.async { applyWindowStyling() }