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fix(iOS, SplitView): Remove tracking presentation layer in favor of sync state update #3285

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fix(iOS, SplitView): Remove tracking presentation layer in favor of sync state update #3285

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4366bb6
Get rid of display link, rely on the final frame with sync update
t0maboro Oct 6, 2025
b5fa5c9
Formatting
t0maboro Oct 6, 2025
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18 changes: 0 additions & 18 deletions ios/gamma/split-view/RNSSplitViewScreenComponentView.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -167,24 +167,6 @@ - (void)safeAreaInsetsDidChange
return react::concreteComponentDescriptorProvider<react::RNSSplitViewScreenComponentDescriptor>();
}

- (void)updateLayoutMetrics:(const facebook::react::LayoutMetrics &)layoutMetrics
oldLayoutMetrics:(const facebook::react::LayoutMetrics &)oldLayoutMetrics
{
// We're tracking presentation layer updates in the RNSSplitViewScreen.
// There's a problem with SplitView that it sets the frame to the end value of the animation right after the animation
// begins. Because of that, the size of our component is desynchronizing easily and we're blocking a communication
// between native and shadow layout for a while until the transition ends. For the following case when we want to make
// a transition from width A to B:
// 1. size 'A' is set on ShadowNode
// 2. animation for the transition starts
// 3. `setFrame` is called with the width 'B'
// 4. in the same time, we want to track updates and treat intermediate value A' indicated from the presentation layer
// as our source of truth
if (![_controller isViewSizeTransitionInProgress]) {
[super updateLayoutMetrics:layoutMetrics oldLayoutMetrics:oldLayoutMetrics];
}
}

+ (BOOL)shouldBeRecycled
{
// There won't be tens of instances of this component usually & it's easier for now.
Expand Down
124 changes: 5 additions & 119 deletions ios/gamma/split-view/RNSSplitViewScreenController.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -18,8 +18,6 @@ public class RNSSplitViewScreenController: UIViewController {
return splitViewScreenComponentView.reactEventEmitter()
}

private var viewSizeTransitionState: ViewSizeTransitionState? = nil

@objc public required init(splitViewScreenComponentView: RNSSplitViewScreenComponentView) {
self.splitViewScreenComponentView = splitViewScreenComponentView
super.init(nibName: nil, bundle: nil)
Expand Down Expand Up @@ -62,18 +60,6 @@ public class RNSSplitViewScreenController: UIViewController {
return self.splitViewController is RNSSplitViewHostController
}

///
/// @brief Determines whether an SplitView animated transition is currently running
///
/// Used to differentiate favor frames from the presentation layer over view's frame .
///
/// @return true if the transition is running, false otherwise.
///
@objc
public func isViewSizeTransitionInProgress() -> Bool {
return viewSizeTransitionState != nil
}

// MARK: Signals

@objc
Expand All @@ -83,55 +69,6 @@ public class RNSSplitViewScreenController: UIViewController {

// MARK: Layout

///
/// @brief This method is overridden to extract the value to which we're transitioning
/// and attach the DisplayLink to track frame updates on the presentation layer.
///
public override func viewWillTransition(
to size: CGSize,
with coordinator: any UIViewControllerTransitionCoordinator
) {
super.viewWillTransition(to: size, with: coordinator)

viewSizeTransitionState = ViewSizeTransitionState()

coordinator.animate(
alongsideTransition: { [weak self] context in
guard let self = self else { return }
guard let viewSizeTransitionState = self.viewSizeTransitionState else { return }

if viewSizeTransitionState.displayLink == nil {
viewSizeTransitionState.setupDisplayLink(
forTarget: self, selector: #selector(trackTransitionProgress))
}
},
completion: { [weak self] context in
guard let self = self else { return }
self.cleanupViewSizeTransitionState()
// After the animation completion, ensure that ShadowTree state
// is calculated relatively to the ancestor's frame by requesting
// the state update.
self.updateShadowTreeState()
})
}

private func cleanupViewSizeTransitionState() {
viewSizeTransitionState?.invalidate()
viewSizeTransitionState = nil
}

///
/// @brief This method is responsible for tracking animation frames and requests layout
/// which will synchronize ShadowNode size with the animation frame size.
///
@objc
private func trackTransitionProgress() {
if let currentFrame = view.layer.presentation()?.frame {
viewSizeTransitionState?.lastViewPresentationFrame = currentFrame
updateShadowTreeState()
}
}

@objc
public override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
Expand All @@ -146,8 +83,6 @@ public class RNSSplitViewScreenController: UIViewController {
/// Differentiates cases when we're in the Host hierarchy to calculate frame relatively
/// to the Host view from the modal case where we're passing absolute layout metrics to the ShadowNode.
///
/// Prefers to apply dynamic updates from the presentation layer if the transition is in progress.
///
private func updateShadowTreeState() {
// For modals, which are presented outside the SplitViewHost subtree (and RN hierarchy),
// we're attaching our touch handler and we don't need to apply any offset corrections,
Expand All @@ -163,48 +98,19 @@ public class RNSSplitViewScreenController: UIViewController {
"[RNScreens] Expected to find RNSSplitViewHost component for RNSSplitViewScreen component"
)

// If the resize animation is currently running, we prefer to apply dynamic updates,
// based on the results from the presentation layer
// which is read from `trackTransitionProgress` method.
if let lastViewPresentationFrame = viewSizeTransitionState?.lastViewPresentationFrame,
!lastViewPresentationFrame.isNull
{
shadowStateProxy.updateShadowState(
ofComponent: splitViewScreenComponentView, withFrame: lastViewPresentationFrame,
inContextOfAncestorView: ancestorView!)
return
}

// There might be the case, when transition is about to start and in the meantime,
// sth else is triggering frame update relatively to the parent. As we know
// that dynamic updates from the presentation layer are coming, we're blocking this
// to prevent interrupting with the frames that are less important for us.
// This works fine, because after the animation completion, we're sending the last update
// which is compatible with the frame which would be calculated relatively to the ancestor here.
if !isViewSizeTransitionInProgress() {
shadowStateProxy.updateShadowState(
ofComponent: splitViewScreenComponentView, inContextOfAncestorView: ancestorView)
}
shadowStateProxy.updateShadowState(
ofComponent: splitViewScreenComponentView, inContextOfAncestorView: ancestorView)
}

///
/// @brief Request ShadowNode state update when the SplitView screen frame origin has changed.
///
/// If there's a transition in progress, this function is ignored as we prefer to apply updates
/// that are dynamically coming from the presentation layer, rather than reading the frame, because
/// view's frame is set to the target value at the begining of the transition.
///
/// @param splitViewController The UISplitViewController whose layout positioning changed, represented by RNSSplitViewHostController.
///
func columnPositioningDidChangeIn(splitViewController: UISplitViewController) {
// During the transition, we're listening for the animation
// frame updates on the presentation layer and we're
// treating these updates as the source of truth
if !isViewSizeTransitionInProgress() {
shadowStateProxy.updateShadowState(
ofComponent: splitViewScreenComponentView, inContextOfAncestorView: splitViewController.view
)
}
shadowStateProxy.updateShadowState(
ofComponent: splitViewScreenComponentView, inContextOfAncestorView: splitViewController.view
)
}

// MARK: Events
Expand Down Expand Up @@ -237,23 +143,3 @@ extension RNSSplitViewScreenController: RNSFrameCorrectionProvider {
self.splitViewScreenComponentView.unregister(fromFrameCorrection: view)
}
}

private class ViewSizeTransitionState {
public var displayLink: CADisplayLink?
public var lastViewPresentationFrame: CGRect = CGRect.null

public func setupDisplayLink(forTarget target: Any, selector sel: Selector) {
if displayLink != nil {
displayLink?.invalidate()
}

displayLink = CADisplayLink(target: target, selector: sel)
displayLink!.add(to: .main, forMode: .common)
}

public func invalidate() {
displayLink?.invalidate()
displayLink = nil
lastViewPresentationFrame = CGRect.null
}
}
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