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feat(ios): RCTViewControllerAppearanceListener #56598

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3b90fd6
feat(ios): RCTViewControllerAppearanceListener
hannojg Apr 24, 2026
6d271eb
simplify
hannojg Apr 24, 2026
f42594f
fix API mismatches
hannojg Apr 24, 2026
94ad872
remove RCTViewController
hannojg Apr 24, 2026
3c03d8e
fix API mismatches
hannojg Apr 24, 2026
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36 changes: 36 additions & 0 deletions packages/react-native/React/Views/UIViewController+React.h
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@@ -0,0 +1,36 @@
/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@protocol RCTViewControllerAppearanceListener <NSObject>

@optional
- (void)reactViewControllerDidAppear:(UIViewController *)viewController animated:(BOOL)animated;
- (void)reactViewControllerDidDisappear:(UIViewController *)viewController animated:(BOOL)animated;

@end

@interface UIViewController (React)

@property (nonatomic, assign, readonly) BOOL reactViewControllerIsVisible;

- (void)reactAddViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener>)listener;
- (void)reactRemoveViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener>)listener;

/**
* Call from `viewDidAppear:` / `viewDidDisappear:` in UIViewController subclasses
* that want to notify registered React Native appearance listeners.
*/
- (void)reactNotifyViewControllerDidAppear:(BOOL)animated;
- (void)reactNotifyViewControllerDidDisappear:(BOOL)animated;

@end

NS_ASSUME_NONNULL_END
89 changes: 89 additions & 0 deletions packages/react-native/React/Views/UIViewController+React.m
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/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/

#import "UIViewController+React.h"

#import <objc/runtime.h>

@interface RCTViewControllerAppearanceState : NSObject

@property (nonatomic, strong, readonly) NSHashTable<id<RCTViewControllerAppearanceListener>> *listeners;
@property (nonatomic, assign) BOOL visible;

@end

@implementation RCTViewControllerAppearanceState

- (instancetype)init
{
if (self = [super init]) {
_listeners = [NSHashTable weakObjectsHashTable];
}
return self;
}

@end

@implementation UIViewController (React)

- (RCTViewControllerAppearanceState *)reactViewControllerAppearanceState
{
RCTViewControllerAppearanceState *state =
objc_getAssociatedObject(self, @selector(reactViewControllerAppearanceState));
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@WoLewicki WoLewicki Apr 24, 2026

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We're doing it in such weird way cause its category right?

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@hannojg hannojg Apr 24, 2026

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yes, unfortunately

if (!state) {
state = [RCTViewControllerAppearanceState new];
objc_setAssociatedObject(
self, @selector(reactViewControllerAppearanceState), state, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
return state;
}

- (BOOL)reactViewControllerIsVisible
{
return [self reactViewControllerAppearanceState].visible;
}

- (void)reactAddViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener>)listener
{
RCTViewControllerAppearanceState *state = [self reactViewControllerAppearanceState];
[state.listeners addObject:listener];

if (state.visible && [listener respondsToSelector:@selector(reactViewControllerDidAppear:animated:)]) {
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@WoLewicki WoLewicki Apr 24, 2026

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Do we need to check the selector? Guess that if it does not implement it then it will just fail silently right?

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@WoLewicki WoLewicki Apr 24, 2026

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Also, why are we dispatching something in the registration method?

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@cipolleschi cipolleschi Apr 24, 2026

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Do we need to check the selector?

Yes, or are we going to get not recognized selector error otherwise.

Also, why are we dispatching something in the registration method

Are you worried that we might not catch all the events?

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@hannojg hannojg Apr 27, 2026 •
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yes, we need the check, otherwise we would get unrecognized selector exception i think 🤔

why are we dispatching something in the registration method?

I think there are two ways to handle this with listener patterns. The question is basically, what should happen if you attach a listener for something that has already happened. Should the listener callback be invoked immediately (the case here), or is it the callers responsibility to check for the condition first (and its for future events only).
I felt like its easier to just send it here so the caller doesn't have to do extra checks + the event is view_Did_Appear, so I felt its reasonable to fire it when the event has already happened. Plus i think it will just make it simpler for the calling site

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@hannojg hannojg Apr 27, 2026

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// Edit: oops, only saw Riccardo's comment now

[listener reactViewControllerDidAppear:self animated:NO];
}
}

- (void)reactRemoveViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener>)listener
{
[[self reactViewControllerAppearanceState].listeners removeObject:listener];
}

- (void)reactNotifyViewControllerDidAppear:(BOOL)animated
{
RCTViewControllerAppearanceState *state = [self reactViewControllerAppearanceState];
state.visible = YES;

for (id<RCTViewControllerAppearanceListener> listener in state.listeners.allObjects) {
if ([listener respondsToSelector:@selector(reactViewControllerDidAppear:animated:)]) {
[listener reactViewControllerDidAppear:self animated:animated];
}
}
}

- (void)reactNotifyViewControllerDidDisappear:(BOOL)animated
{
RCTViewControllerAppearanceState *state = [self reactViewControllerAppearanceState];
state.visible = NO;

for (id<RCTViewControllerAppearanceListener> listener in state.listeners.allObjects) {
if ([listener respondsToSelector:@selector(reactViewControllerDidDisappear:animated:)]) {
[listener reactViewControllerDidDisappear:self animated:animated];
}
}
}

@end
1 change: 1 addition & 0 deletions packages/react-native/scripts/ios-prebuild/templates/React-umbrella.h
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Expand Up @@ -283,6 +283,7 @@
#import <React/RCTWrapperViewController.h>
#import <React/UIView+Private.h>
#import <React/UIView+React.h>
#import <React/UIViewController+React.h>

FOUNDATION_EXPORT double ReactVersionNumber;
FOUNDATION_EXPORT const unsigned char ReactVersionString[];
13 changes: 13 additions & 0 deletions scripts/cxx-api/api-snapshots/ReactAppleDebugCxx.api
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Expand Up @@ -325,6 +325,14 @@ category UIView(React) {
public virtual void removeReactSubview:(UIView* subview);
}

category UIViewController(React) {
public @property (assign, readonly) BOOL reactViewControllerIsVisible;
public virtual void reactAddViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener> listener);
public virtual void reactNotifyViewControllerDidAppear:(BOOL animated);
public virtual void reactNotifyViewControllerDidDisappear:(BOOL animated);
public virtual void reactRemoveViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener> listener);
}

class ObjCTimerRegistry : public facebook::react::PlatformTimerRegistry {
public ObjCTimerRegistry();
public RCTTiming* _Null_unspecified timing;
Expand Down Expand Up @@ -3493,6 +3501,11 @@ protocol RCTValueAnimatedNodeObserver : public NSObject {
public virtual void animatedNode:didUpdateValue:(RCTValueAnimatedNode* node, CGFloat value);
}

protocol RCTViewControllerAppearanceListener : public NSObject {
public virtual void reactViewControllerDidAppear:animated:(UIViewController* viewController, BOOL animated);
public virtual void reactViewControllerDidDisappear:animated:(UIViewController* viewController, BOOL animated);
}

protocol RCTVirtualViewContainerProtocol {
public virtual RCTVirtualViewContainerState* virtualViewContainerState();
}
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13 changes: 13 additions & 0 deletions scripts/cxx-api/api-snapshots/ReactAppleReleaseCxx.api
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Expand Up @@ -325,6 +325,14 @@ category UIView(React) {
public virtual void removeReactSubview:(UIView* subview);
}

category UIViewController(React) {
public @property (assign, readonly) BOOL reactViewControllerIsVisible;
public virtual void reactAddViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener> listener);
public virtual void reactNotifyViewControllerDidAppear:(BOOL animated);
public virtual void reactNotifyViewControllerDidDisappear:(BOOL animated);
public virtual void reactRemoveViewControllerAppearanceListener:(id<RCTViewControllerAppearanceListener> listener);
}

class ObjCTimerRegistry : public facebook::react::PlatformTimerRegistry {
public ObjCTimerRegistry();
public RCTTiming* _Null_unspecified timing;
Expand Down Expand Up @@ -3493,6 +3501,11 @@ protocol RCTValueAnimatedNodeObserver : public NSObject {
public virtual void animatedNode:didUpdateValue:(RCTValueAnimatedNode* node, CGFloat value);
}

protocol RCTViewControllerAppearanceListener : public NSObject {
public virtual void reactViewControllerDidAppear:animated:(UIViewController* viewController, BOOL animated);
public virtual void reactViewControllerDidDisappear:animated:(UIViewController* viewController, BOOL animated);
}

protocol RCTVirtualViewContainerProtocol {
public virtual RCTVirtualViewContainerState* virtualViewContainerState();
}
Expand Down
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