fix(ios): render dim in presenter view when presenter VC is detached

When TrueSheet is presented from a UIViewController that is not reachable
from the key window's root VC via the parent/presentingViewController
chain, UIKit's built-in UISheetPresentationController dim layer lands in
the wrong UIWindow — the sheet content renders correctly but the dim
appears in a fallback container instead of behind the sheet.

iOS surfaces this at runtime as:
  "Presenting view controller ... from detached view controller ... is
   not supported, and may result in incorrect safe area insets and a
   corrupt root presentation."

Detachment is inherited up the chain: a VC can have a non-nil
presentingViewController but still be detached if that presenter is
itself detached. A single-level check is not sufficient.

Two changes:

1. findPresentingViewController walks superview.nextResponder to locate
   the nearest ancestor VC. This correctly finds VCs parked in the view
   tree by custom navigators (which may use addSubview: rather than
   modal presentation), where the previous window.rootViewController
   presentedViewController chain walk would miss them.

2. Added isPresenterDetached: which walks parent/presenting chain until
   it reaches the window's root VC. When the presenter is detached AND
   dimmed is YES, we add a fallback dim UIView as a subview of the
   presenter's view so it lives in the correct window below the
   natively-presented sheet. The dim is removed (animated) in
   dismissAnimated:, viewControllerWillDismiss, prepareForRecycle, and
   dealloc so every dismissal path — including swipe-dismiss and Fabric
   view recycling — cleans up correctly.

No behavior change for the attached-presenter path.

Closes #661

Author: kanzelm3

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 ### 🐛 Bug fixes
 
+- **iOS**: Fixed sheet dim rendering in the wrong `UIWindow` when the presenter view controller is detached from the window's VC hierarchy (e.g. inside a custom navigator or RN `<Modal>`). `findPresentingViewController` now walks the responder chain to find the real owning VC, and a fallback dim view is added to the presenter's view when the presenter is detached. ([#TBD](https://github.com/lodev09/react-native-true-sheet/pull/TBD) by [@kanzelm3](https://github.com/kanzelm3))
 - **Android**: Fixed focused input in sheet causing auto-focus on main screen input after dismiss. ([#649](https://github.com/lodev09/react-native-true-sheet/pull/649) by [@lodev09](https://github.com/lodev09))
 
 ## 3.10.0

ios/TrueSheetView.mm

@@ -65,6 +65,10 @@ @implementation TrueSheetView {
   BOOL _pendingPropsUpdate;
   NSArray *_pendingDetents;
   RNScreensEventObserver *_screensEventObserver;
+  // Fallback dim view used when the presenter VC is detached from the window's
+  // VC hierarchy — UIKit's built-in sheet dim renders in the wrong UIWindow in
+  // that case, so we render our own in the presenter's view instead.
+  UIView *_detachedPresenterDimView;
 }
 
 #pragma mark - Initialization
@@ -148,6 +152,9 @@ - (void)dealloc {
   [_snapshotView removeFromSuperview];
   _snapshotView = nil;
 
+  [_detachedPresenterDimView removeFromSuperview];
+  _detachedPresenterDimView = nil;
+
   [TrueSheetModule unregisterViewWithTag:@(self.tag)];
 }
 
@@ -332,6 +339,9 @@ - (void)prepareForRecycle {
 
   [TrueSheetModule unregisterViewWithTag:@(self.tag)];
 
+  [_detachedPresenterDimView removeFromSuperview];
+  _detachedPresenterDimView = nil;
+
   _lastStateSize = CGSizeZero;
   _didInitiallyPresent = NO;
   _dismissedByNavigation = NO;
@@ -449,6 +459,12 @@ - (void)presentAtIndex:(NSInteger)index
   [_screensEventObserver capturePresenterScreenFromView:self];
   [_screensEventObserver startObservingWithState:_state.get()->getData()];
 
+  // If the presenter VC is detached from the window's VC hierarchy, UIKit's
+  // built-in sheet dim renders in the wrong UIWindow. Add our own dim as a
+  // subview of the presenter's view so it lives in the correct window below
+  // the natively-presented sheet.
+  [self addDetachedPresenterDimIfNeededForPresenter:presentingViewController animated:animated];
+
   [presentingViewController presentViewController:_controller
                                          animated:animated
                                        completion:^{
@@ -458,6 +474,90 @@ - (void)presentAtIndex:(NSInteger)index
                                        }];
 }
 
+- (BOOL)isPresenterDetached:(UIViewController *)presenter {
+  // A VC is attached if we can walk up its parent/presenting chain and reach
+  // the window's root VC. Detachment is *inherited* — a VC can have a non-nil
+  // `presentingViewController` but still be detached if that presenter is
+  // itself detached. UIKit applies the same rule and emits "Presenting view
+  // controller ... from detached view controller ..." in that case.
+  if (!presenter) {
+    return NO;
+  }
+  UIWindow *window = presenter.viewIfLoaded.window ?: self.window;
+  UIViewController *rootVC = window.rootViewController;
+  NSMutableSet *visited = [NSMutableSet set];
+  UIViewController *current = presenter;
+  while (current) {
+    if (current == rootVC) {
+      return NO;  // reached the root — attached
+    }
+    if ([visited containsObject:current]) {
+      return YES;  // cycle guard — treat as detached
+    }
+    [visited addObject:current];
+    // Walk up: prefer containment parent, fall back to modal presenter.
+    UIViewController *next = current.parentViewController;
+    if (!next) {
+      next = current.presentingViewController;
+    }
+    current = next;
+  }
+  return YES;  // chain ends before root — detached
+}
+
+- (void)addDetachedPresenterDimIfNeededForPresenter:(UIViewController *)presenter animated:(BOOL)animated {
+  if (!_controller.dimmed) {
+    return;
+  }
+  if (![self isPresenterDetached:presenter]) {
+    return;
+  }
+  if (!presenter.isViewLoaded) {
+    return;
+  }
+
+  UIView *dim = [[UIView alloc] initWithFrame:presenter.view.bounds];
+  dim.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.4];
+  dim.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+  dim.alpha = 0.0;
+  dim.userInteractionEnabled = NO;
+  [presenter.view addSubview:dim];
+
+  _detachedPresenterDimView = dim;
+
+  CGFloat duration = animated ? 0.35 : 0.0;
+  [UIView animateWithDuration:duration
+                        delay:0.0
+                      options:UIViewAnimationOptionCurveEaseInOut
+                   animations:^{
+                     dim.alpha = 0.4;
+                   }
+                   completion:nil];
+}
+
+- (void)removeDetachedPresenterDimAnimated:(BOOL)animated {
+  UIView *dim = _detachedPresenterDimView;
+  if (!dim) {
+    return;
+  }
+  _detachedPresenterDimView = nil;
+
+  if (!animated) {
+    [dim removeFromSuperview];
+    return;
+  }
+
+  [UIView animateWithDuration:0.35
+    delay:0.0
+    options:UIViewAnimationOptionCurveEaseInOut
+    animations:^{
+      dim.alpha = 0.0;
+    }
+    completion:^(BOOL finished) {
+      [dim removeFromSuperview];
+    }];
+}
+
 - (void)resizeToIndex:(NSInteger)index completion:(nullable TrueSheetCompletionBlock)completion {
   if (!_controller.isPresented) {
     RCTLogWarn(@"TrueSheet: Cannot resize. Sheet is not presented.");
@@ -498,6 +598,10 @@ - (void)dismissAnimated:(BOOL)animated completion:(nullable TrueSheetCompletionB
     return;
   }
 
+  // Fade out the detached-presenter dim (if any) in lockstep with the sheet
+  // animation so it's gone by the time the sheet finishes dismissing.
+  [self removeDetachedPresenterDimAnimated:animated];
+
   // Dismiss from the presenting view controller to dismiss this sheet and all its children
   UIViewController *presenter = _controller.presentingViewController;
   [presenter dismissViewControllerAnimated:animated
@@ -618,6 +722,11 @@ - (void)viewControllerDidDrag:(UIGestureRecognizerState)state
 }
 
 - (void)viewControllerWillDismiss {
+  // Also fade out the detached-presenter dim for swipe-dismiss and other paths
+  // that don't go through dismissAnimated: — willDismiss fires once the
+  // dismissal transition begins regardless of what triggered it.
+  [self removeDetachedPresenterDimAnimated:YES];
+
   if (!_dismissedByNavigation) {
     [TrueSheetLifecycleEvents emitWillDismiss:_eventEmitter];
   }
@@ -734,7 +843,24 @@ - (UIViewController *)findPresentingViewController {
   if (!self.window)
     return nil;
 
-  UIViewController *rootViewController = self.window.rootViewController;
+  // Walk the view hierarchy to find the nearest ancestor view controller.
+  // Some navigators (e.g. React Navigation's custom navigators, RN's `<Modal>`
+  // nested inside one) attach their VCs to the tree via `addSubview:` rather
+  // than modal presentation, so `window.rootViewController.presentedViewController`
+  // never reaches them. Walking `superview.nextResponder` finds the real
+  // owning VC of the view we're in.
+  UIView *ancestor = self.superview;
+  UIViewController *nearestVC = nil;
+  while (ancestor) {
+    UIResponder *responder = ancestor.nextResponder;
+    if ([responder isKindOfClass:[UIViewController class]]) {
+      nearestVC = (UIViewController *)responder;
+      break;
+    }
+    ancestor = ancestor.superview;
+  }
+
+  UIViewController *rootViewController = nearestVC ?: self.window.rootViewController;
   if (!rootViewController)
     return nil;