fix an UI issue of navigation bar

Session/Conversations/ConversationVC.swift

@@ -142,7 +142,6 @@ final class ConversationVC: BaseVC, LibSessionRespondingViewController, Conversa
         result.separatorStyle = .none
         result.themeBackgroundColor = .clear
         result.showsVerticalScrollIndicator = false
-        result.contentInsetAdjustmentBehavior = .never
         result.keyboardDismissMode = .interactive
         result.contentInset = UIEdgeInsets(
             top: 0,

SessionUIKit/Style Guide/ThemeManager.swift

@@ -150,6 +150,30 @@ public enum ThemeManager {
         ThemeManager.mainWindow?.tintColor = textPrimary
         ThemeManager.mainWindow?.rootViewController?.setNeedsStatusBarAppearanceUpdate()
         
+        // Update the nav bars to use the right colours (we default to the 'primary' value)
+        UINavigationBar.appearance().barTintColor = ThemeManager.currentTheme.color(for: .backgroundPrimary)
+        UINavigationBar.appearance().isTranslucent = false
+        UINavigationBar.appearance().tintColor = textPrimary
+        UINavigationBar.appearance().shadowImage = ThemeManager.currentTheme.color(for: .backgroundPrimary)?.toImage()
+        UINavigationBar.appearance().titleTextAttributes = [
+            NSAttributedString.Key.foregroundColor: textPrimary
+        ]
+        UINavigationBar.appearance().largeTitleTextAttributes = [
+            NSAttributedString.Key.foregroundColor: textPrimary
+        ]
+        
+        // Update the bar button item appearance
+        UIBarButtonItem.appearance().tintColor = textPrimary
+
+        // Update toolbars to use the right colours
+        UIToolbar.appearance().barTintColor = ThemeManager.currentTheme.color(for: .backgroundPrimary)
+        UIToolbar.appearance().isTranslucent = false
+        UIToolbar.appearance().tintColor = textPrimary
+        
+        // Note: Looks like there were changes to the appearance behaviour in iOS 15, unfortunately
+        // this breaks parts of the old 'UINavigationBar.appearance()' logic so we need to do everything
+        // again using the new API...
+        if #available(iOS 15.0, *) {
             let appearance = UINavigationBarAppearance()
             appearance.configureWithOpaqueBackground()
             appearance.backgroundColor = ThemeManager.currentTheme.color(for: .backgroundPrimary)
@@ -173,11 +197,7 @@ public enum ThemeManager {
             
             UINavigationBar.appearance().standardAppearance = appearance
             UINavigationBar.appearance().scrollEdgeAppearance = appearance
-
+        }
-        // Update toolbars to use the right colours
-        UIToolbar.appearance().barTintColor = ThemeManager.currentTheme.color(for: .backgroundPrimary)
-        UIToolbar.appearance().isTranslucent = false
-        UIToolbar.appearance().tintColor = textPrimary
         
         // Note: 'UINavigationBar.appearance' only affects newly created nav bars so we need
         // to force-update any current navigation bar (unfortunately the only way to do this
@@ -231,6 +251,13 @@ public enum ThemeManager {
             let navigationBackground: ThemeValue = (navController.viewControllers.first as? ThemedNavigation)?.navigationBackground
         else { return }
         
+        navController.navigationBar.barTintColor = ThemeManager.currentTheme.color(for: navigationBackground)
+        navController.navigationBar.shadowImage = ThemeManager.currentTheme.color(for: navigationBackground)?.toImage()
+        
+        // Note: Looks like there were changes to the appearance behaviour in iOS 15, unfortunately
+        // this breaks parts of the old 'UINavigationBar.appearance()' logic so we need to do everything
+        // again using the new API...
+        if #available(iOS 15.0, *) {
             let textPrimary: UIColor = (ThemeManager.currentTheme.color(for: .textPrimary) ?? .white)
             let appearance = UINavigationBarAppearance()
             appearance.configureWithOpaqueBackground()
@@ -246,6 +273,7 @@ public enum ThemeManager {
             navController.navigationBar.standardAppearance = appearance
             navController.navigationBar.scrollEdgeAppearance = appearance
         }
+    }
     
     private static func retrieveNavigationController(from viewController: UIViewController) -> UINavigationController? {
         switch viewController {