From 1ac749ed4ae39f384623de893ba5bd8fa71df38e Mon Sep 17 00:00:00 2001
From: Bao Nguyen <waycaosi1994@gmail.com>
Date: Wed, 12 Aug 2026 11:52:29 +0700
Subject: [PATCH] fix(ios): hit-test nested scrollables from the touch-down
 point

The checks deciding whether the sheet or a nested scrollable owns a pan
read panGesture.location(in: sheetContainer) inside
gestureRecognizerShouldBegin and handlePan(.began), i.e. after UIKit's
pan translation threshold has been exceeded. That is the finger's
current location, not the touch-down point, so when the draggable chrome
above a scrollable is short, the threshold movement carries the point
into the scrollable's frame before the check runs and the sheet refuses
a drag aimed at the handle.

Record the touch-down location in gestureRecognizer(_:shouldReceive:)
and resolve the scrollable chain from that stored point instead,
matching Android's ACTION_DOWN semantics (initialTouchX/initialTouchY).

Fixes #63
---
 ios/BottomSheetHostingView.swift | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/ios/BottomSheetHostingView.swift b/ios/BottomSheetHostingView.swift
index 5dff2de..a88bb52 100644
--- a/ios/BottomSheetHostingView.swift
+++ b/ios/BottomSheetHostingView.swift
@@ -177,6 +177,7 @@ public final class BottomSheetHostingView: UIView {
   private var isPanning = false
   private var lastReportedInvalidDetentMessage: String?
   private var panStartingIndex: Int?
+  private var initialTouchLocation: CGPoint?
   private var activeDragRange: (minTy: CGFloat, maxTy: CGFloat)?
   private var activeDragDetentSpecs: [DetentSpec]?
   private var activeScrollViewStates: [ActiveScrollViewState] = []
@@ -881,7 +882,7 @@ public final class BottomSheetHostingView: UIView {
       scrollViewOwnsLowerBoundary = false
       activeScrollableNegotiationLevel = negotiationLevel(forVerticalVelocity: gesture.velocity(in: self).y)
 
-      let locationInContainer = gesture.location(in: sheetContainer)
+      let locationInContainer = initialTouchLocation ?? gesture.location(in: sheetContainer)
       activeScrollViewStates = scrollableAncestorChain(containing: locationInContainer).map {
         ActiveScrollViewState(scrollView: $0.scrollView, inverted: $0.inverted)
       }
@@ -1227,7 +1228,7 @@ public final class BottomSheetHostingView: UIView {
     let candidates = snapCandidateIndices(including: targetIndex)
     guard candidates.count > 1 else { return false }
 
-    let locationInContainer = panGesture.location(in: sheetContainer)
+    let locationInContainer = initialTouchLocation ?? panGesture.location(in: sheetContainer)
     let scrollableChain = scrollableAncestorChain(containing: locationInContainer)
     guard !scrollableChain.isEmpty else {
       // Outside a scrollable, the sheet owns any direction in which it has a
@@ -1561,6 +1562,20 @@ extension BottomSheetHostingView: UIGestureRecognizerDelegate {
     return true
   }
 
+  public func gestureRecognizer(
+    _ gestureRecognizer: UIGestureRecognizer,
+    shouldReceive touch: UITouch
+  ) -> Bool {
+    // Record the touch-down point before the pan's translation threshold is
+    // exceeded. gestureRecognizerShouldBegin and handlePan(.began) hit-test
+    // scrollables from this point instead of the post-threshold pan location,
+    // matching Android's ACTION_DOWN semantics.
+    if gestureRecognizer === panGesture, panGesture.numberOfTouches == 0 {
+      initialTouchLocation = touch.location(in: sheetContainer)
+    }
+    return true
+  }
+
   public func gestureRecognizer(
     _ gestureRecognizer: UIGestureRecognizer,
     shouldBeRequiredToFailBy other: UIGestureRecognizer