Sink event and interactions in nested stack

Author: kmichalikk

ios/RNSScreenStack.mm

@@ -29,6 +29,7 @@
 #import "RNSScreenWindowTraits.h"
 #import "RNSScrollViewFinder.h"
 #import "RNSTabsScreenViewController.h"
+#import "RNSViewInteractionAware.h"
 #import "UIScrollView+RNScreens.h"
 #import "UIView+RNSUtility.h"
 #import "integrations/RNSDismissibleModalProtocol.h"
@@ -47,7 +48,8 @@ @interface RNSScreenStackView () <
     UINavigationControllerDelegate,
     UIAdaptivePresentationControllerDelegate,
     UIGestureRecognizerDelegate,
-    UIViewControllerTransitioningDelegate
+    UIViewControllerTransitioningDelegate,
+    RNSViewInteractionAware
 #ifdef RCT_NEW_ARCH_ENABLED
     ,
     RCTMountingTransactionObserving
@@ -259,6 +261,7 @@ @implementation RNSScreenStackView {
   RNSPercentDrivenInteractiveTransition *_interactionController;
   __weak RNSScreenStackManager *_manager;
   BOOL _updateScheduled;
+  UIPanGestureRecognizer *_sinkEventsPanGestureRecognizer;
 #ifdef RCT_NEW_ARCH_ENABLED
   /// Screens that are subject of `ShadowViewMutation::Type::Delete` mutation
   /// in current transaction. This vector should be populated when we receive notification via
@@ -304,6 +307,7 @@ - (void)initCommonProps
   _presentedModals = [NSMutableArray new];
   _controller = [RNSNavigationController new];
   _controller.delegate = self;
+  _sinkEventsPanGestureRecognizer = [[UIPanGestureRecognizer alloc] init];
 #if !TARGET_OS_TV && !TARGET_OS_VISION
   [self setupGestureHandlers];
 #endif
@@ -899,6 +903,20 @@ - (void)cancelTouchesInParent
   [[self rnscreens_findTouchHandlerInAncestorChain] rnscreens_cancelTouches];
 }
 
+- (void)disableInteractions
+{
+  // When transitioning between screens, disable interactions on stack subview which wraps the screens
+  // and sink all gesture events. This should work for nested stacks and stack inside bottom tabs, inside stack.
+  self.subviews[0].userInteractionEnabled = NO;
+  [self addGestureRecognizer:_sinkEventsPanGestureRecognizer];
+}
+
+- (void)enableInteractions
+{
+  self.subviews[0].userInteractionEnabled = YES;
+  [self removeGestureRecognizer:_sinkEventsPanGestureRecognizer];
+}
+
 - (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
 {
   if (_disableSwipeBack) {
@@ -1265,6 +1283,15 @@ - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
 - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
     shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
 {
+  if (otherGestureRecognizer == _sinkEventsPanGestureRecognizer) {
+    // When transition happens between two stack screens, a special "sink" recognizer is added, and then removed.
+    // It captures all gestures for the time of transition and does nothing, so that in nested stack scenario,
+    // the outer most stack does not recognize swipe gestures, otherwise it would dismiss the whole nested stack.
+    // For the recognizer to work as described, it should have precedence over all other recognizers.
+    // see also: enableInteractions, disableInteractions
+    return YES;
+  }
+
   if (@available(iOS 26, *)) {
     if (gestureRecognizer == _controller.interactiveContentPopGestureRecognizer &&
         [self isScrollViewPanGestureRecognizer:otherGestureRecognizer]) {

ios/helpers/RNSViewInteractionAware.h

@@ -0,0 +1,9 @@
+#pragma once
+
+@protocol RNSViewInteractionAware
+
+- (void)disableInteractions;
+
+- (void)enableInteractions;
+
+@end

ios/helpers/RNSViewInteractionManager.h

@@ -5,10 +5,9 @@
 - (instancetype)init;
 
 /**
- * Given a view, find a nearest parent on which it is safe to disable interactions, when transitioning between screens
- * in stack. When Stack is nested inside BottomTabs, it finds such view that the tabs are still interactive. Otherwise,
- * it will default to UIWindow. Makes sure that at most one view is disabled at any time, re-enabling interactions on
- * previously affected views.
+ * Given a view, traverse its ancestors hierarchy and find a view that supports RNSViewInteractionAware protocol
+ * and can disable interactions for the time of screen transition. Make sure that at most one view is disabled at any
+ * time, re-enabling interactions on previously affected views when necessary.
  */
 - (void)disableInteractionsForSubtreeWith:(UIView *)view;
 

ios/helpers/RNSViewInteractionManager.mm

@@ -1,5 +1,6 @@
 #import "RNSViewInteractionManager.h"
 #import "RNSBottomTabsScreenComponentView.h"
+#import "RNSViewInteractionAware.h"
 
 @implementation RNSViewInteractionManager {
   __weak UIView *lastRootWithInteractionsDisabled;
@@ -13,28 +14,38 @@ - (instancetype)init
 
 - (void)disableInteractionsForSubtreeWith:(UIView *)view
 {
-  UIView *parent = view.superview;
-  while (parent && ![parent isKindOfClass:UIWindow.class] &&
-         ![parent isKindOfClass:RNSBottomTabsScreenComponentView.class]) {
-    parent = parent.superview;
+  UIView *current = view;
+  while (current && ![current isKindOfClass:UIWindow.class] &&
+         ![current respondsToSelector:@selector(disableInteractions)]) {
+    current = current.superview;
   }
 
-  if (parent) {
-    if (lastRootWithInteractionsDisabled && lastRootWithInteractionsDisabled != parent) {
+  if (current) {
+    if (lastRootWithInteractionsDisabled && lastRootWithInteractionsDisabled != current) {
       // When one view already has interactions disabled, and we request a different view,
       // we need to restore the first one
-      lastRootWithInteractionsDisabled.userInteractionEnabled = YES;
+      [self enableInteractionsForLastSubtree];
+    }
+
+    if ([current respondsToSelector:@selector(disableInteractions)]) {
+      [static_cast<id<RNSViewInteractionAware>>(current) disableInteractions];
+    } else {
+      current.userInteractionEnabled = NO;
     }
 
-    parent.userInteractionEnabled = NO;
-    lastRootWithInteractionsDisabled = parent;
+    lastRootWithInteractionsDisabled = current;
   }
 }
 
 - (void)enableInteractionsForLastSubtree
 {
   if (lastRootWithInteractionsDisabled) {
-    lastRootWithInteractionsDisabled.userInteractionEnabled = YES;
+    if ([lastRootWithInteractionsDisabled respondsToSelector:@selector(enableInteractions)]) {
+      [static_cast<id<RNSViewInteractionAware>>(lastRootWithInteractionsDisabled) enableInteractions];
+    } else {
+      lastRootWithInteractionsDisabled.userInteractionEnabled = YES;
+    }
+
     lastRootWithInteractionsDisabled = nil;
   }
 }