Skip to content

Fix LegacyViewManagerInterop unmounting the wrong child, and mounting children late, in a hosted legacy view #59005

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
habovh wants to merge 2 commits into
base: main
Choose a base branch
from
Open

Fix LegacyViewManagerInterop unmounting the wrong child, and mounting children late, in a hosted legacy view #59005

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
e83e491
Fix LegacyViewManagerInterop unmounting the wrong child of a legacy view
habovh Oct 11, 2026
7c0f70c
Mount children of a legacy view right away so its children stay in st…
habovh Oct 11, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
45 changes: 33 additions & 12 deletions ...nting/ComponentViews/LegacyViewManagerInterop/RCTLegacyViewManagerInteropComponentView.mm
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -173,17 +173,19 @@ - (void)prepareForRecycle

- (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index
{
if (_adapter && index == _adapter.paperView.reactSubviews.count) {
// This is a new child view that is being added to the end of the children array.
// After the children is added, we need to call didUpdateReactSubviews to make sure that it is rendered.
// Without this change, the new child will not be rendered right away because the didUpdateReactSubviews is not
// called and the `finalizeUpdate` is not invoked.
if (_adapter) {
// The child is inserted right away, wherever it goes, so that the paper view's `reactSubviews` stay in step with
// the Fabric children. A mount that waited for `finalizeUpdates:` would be applied late (the host view is not
// updated by every transaction that changes its children) and would shift the position of every later child. After
// the child is added, we need to call didUpdateReactSubviews to make sure that it is rendered. Without this change,
// the new child will not be rendered right away because the didUpdateReactSubviews is not called and the
// `finalizeUpdate` is not invoked.
UIView *target = childComponentView;
if ([childComponentView isKindOfClass:[RCTLegacyViewManagerInteropComponentView class]]) {
UIView *target = ((RCTLegacyViewManagerInteropComponentView *)childComponentView).contentView;
[_adapter.paperView insertReactSubview:target atIndex:index];
} else {
[_adapter.paperView insertReactSubview:childComponentView atIndex:index];
target = ((RCTLegacyViewManagerInteropComponentView *)childComponentView).contentView;
}
[_adapter.paperView insertReactSubview:target
atIndex:MIN(index, (NSInteger)_adapter.paperView.reactSubviews.count)];
[_adapter.paperView didUpdateReactSubviews];
} else {
[_viewsToBeMounted addObject:@{
Expand All @@ -195,10 +197,29 @@ - (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childCompone

- (void)unmountChildComponentView:(UIView<RCTComponentViewProtocol> *)childComponentView index:(NSInteger)index
{
if (_adapter && index < _adapter.paperView.reactSubviews.count) {
[_adapter.paperView removeReactSubview:_adapter.paperView.reactSubviews[index]];
// The child named by the mutation is looked up instead of using `index` as a position in the paper view's
// `reactSubviews`: the two differ whenever a mount is still queued in `_viewsToBeMounted`.

// A child whose mount is still queued never reached the paper view: forget the mount.
for (NSDictionary *mountInstruction in [_viewsToBeMounted copy]) {
if (mountInstruction[kRCTLegacyInteropChildComponentKey] == childComponentView) {
[_viewsToBeMounted removeObject:mountInstruction];
return;
}
}

// `mountChildComponentView:index:` inserts the content view of a child that is itself an interop view.
UIView *target = childComponentView;
if ([childComponentView isKindOfClass:[RCTLegacyViewManagerInteropComponentView class]]) {
target = ((RCTLegacyViewManagerInteropComponentView *)childComponentView).contentView ?: childComponentView;
}

if (_adapter && [_adapter.paperView.reactSubviews containsObject:target]) {
// Removed right away: a `Delete` mutation of this child in the same transaction recycles it before
// `finalizeUpdates:` runs, and a recycled view must not have a superview.
[_adapter.paperView removeReactSubview:target];
} else {
[_viewsToBeUnmounted addObject:childComponentView];
[_viewsToBeUnmounted addObject:target];
}
}

Expand Down
Loading