addressing comments

shell/platform/darwin/ios/framework/Source/SemanticsObject.mm

@@ -274,17 +274,16 @@ - (BOOL)isAccessibilityElement {
   if ([self node].HasFlag(flutter::SemanticsFlags::kScopesRoute))
     return false;
 
-  // If the only flag(s) set are scrolling related AND
-  // The only flags set are not kIsHidden OR
-  // The node doesn't have a label, value, or hint OR
-  // The only actions set are scrolling related actions.
+  // If the node is scrollable AND hidden OR
+  // The node has a label, value, or hint OR
+  // The node has non-scrolling related actions.
   //
-  // The kIsHidden flag set with any other flag just means this node is now
+  // The kIsHidden flag set with the scrollable flag means this node is now
   // hidden but still is a valid target for a11y focus in the tree, e.g. a list
   // item that is currently off screen but the a11y navigation needs to know
   // about.
-  return (([self node].flags & ~flutter::kScrollableSemanticsFlags) != 0 &&
-          ([self node].flags & ~static_cast<int32_t>(flutter::SemanticsFlags::kIsHidden)) != 1) ||
+  return (([self node].flags & flutter::kScrollableSemanticsFlags) != 0 &&
+          ([self node].flags & static_cast<int32_t>(flutter::SemanticsFlags::kIsHidden)) != 0) ||
          ![self node].label.empty() || ![self node].value.empty() || ![self node].hint.empty() ||
          ([self node].actions & ~flutter::kScrollableSemanticsActions) != 0;
 }

shell/platform/darwin/ios/framework/Source/accessibility_bridge.h

@@ -78,7 +78,12 @@ class AccessibilityBridge final : public AccessibilityBridgeIos {
 
  private:
   SemanticsObject* GetOrCreateObject(int32_t id, flutter::SemanticsNodeUpdates& updates);
-  SemanticsObject* FindFirstFocusable(SemanticsObject* object);
+  SemanticsObject* FindNextFocusableIfNecessary();
+  // Finds the first focusable SemanticsObject rooted at the parent. This includes the parent itself
+  // if it is a focusable SemanticsObject.
+  //
+  // If the parent is nil, this function use the root SemanticsObject as the parent.
+  SemanticsObject* FindFirstFocusable(SemanticsObject* parent);
   void VisitObjectsRecursivelyAndRemove(SemanticsObject* object,
                                         NSMutableArray<NSNumber*>* doomed_uids);
   void HandleEvent(NSDictionary<NSString*, id>* annotatedEvent);

shell/platform/darwin/ios/framework/Source/accessibility_bridge.mm

@@ -216,35 +216,14 @@ void PostAccessibilityNotification(UIAccessibilityNotifications notification,
   }
 
   if (layoutChanged) {
-    SemanticsObject* nextToFocus = nil;
-    // This property will be -1 if the focus is outside of the flutter
-    // application. In this case, we should not refocus anything.
-    if (last_focused_semantics_object_id_ != kSemanticObjectIdInvalid) {
-      // Tries to refocus the previous focused semantics object to avoid random jumps.
-      nextToFocus = [objects_.get() objectForKey:@(last_focused_semantics_object_id_)];
-      if (nextToFocus) {
-        nextToFocus = FindFirstFocusable(nextToFocus);
-      } else if (root) {
-        nextToFocus = FindFirstFocusable(root);
-      }
-    }
     ios_delegate_->PostAccessibilityNotification(UIAccessibilityLayoutChangedNotification,
-                                                 nextToFocus);
+                                                 FindNextFocusableIfNecessary());
   } else if (scrollOccured) {
     // TODO(chunhtai): figure out what string to use for notification. At this
     // point, it is guarantee the previous focused object is still in the tree
     // so that we don't need to worry about focus lost. (e.g. "Screen 0 of 3")
-    SemanticsObject* nextToFocus = nil;
-    if (last_focused_semantics_object_id_ != kSemanticObjectIdInvalid) {
-      nextToFocus = [objects_.get() objectForKey:@(last_focused_semantics_object_id_)];
-      if (nextToFocus) {
-        nextToFocus = FindFirstFocusable(nextToFocus);
-      } else if (root) {
-        nextToFocus = FindFirstFocusable(root);
-      }
-    }
     ios_delegate_->PostAccessibilityNotification(UIAccessibilityPageScrolledNotification,
-                                                 nextToFocus);
+                                                 FindNextFocusableIfNecessary());
   }
 }
 
@@ -328,12 +307,28 @@ static bool DidFlagChange(const flutter::SemanticsNode& oldNode,
     VisitObjectsRecursivelyAndRemove(child, doomed_uids);
 }
 
-SemanticsObject* AccessibilityBridge::FindFirstFocusable(SemanticsObject* object) {
-  if (object.isAccessibilityElement) {
-    return object;
+SemanticsObject* AccessibilityBridge::FindNextFocusableIfNecessary() {
+  // This property will be -1 if the focus is outside of the flutter
+  // application. In this case, we should not refocus anything.
+  if (last_focused_semantics_object_id_ == kSemanticObjectIdInvalid) {
+    return nil;
+  }
+
+  // Tries to refocus the previous focused semantics object to avoid random jumps.
+  return FindFirstFocusable([objects_.get() objectForKey:@(last_focused_semantics_object_id_)]);
+}
+
+SemanticsObject* AccessibilityBridge::FindFirstFocusable(SemanticsObject* parent) {
+  SemanticsObject* currentObject = parent ?: objects_.get()[@(kRootNodeId)];
+  ;
+  if (!currentObject)
+    return nil;
+
+  if (currentObject.isAccessibilityElement) {
+    return currentObject;
   }
 
-  for (SemanticsObject* child in [object children]) {
+  for (SemanticsObject* child in [currentObject children]) {
     SemanticsObject* candidate = FindFirstFocusable(child);
     if (candidate) {
       return candidate;