fix(ios): respect scrollEnabled on iOS 15

ios/PagerView.swift

@@ -16,6 +16,18 @@ struct PagerView: View {
     props.orientation == .vertical
   }
 
+  private func applyScrollEnabled(_ scrollEnabled: Bool) {
+    collectionView?.isScrollEnabled = scrollEnabled
+    // iOS 15 only, see PagerViewIOS15Compat.swift (delete together with the iOS 15 support).
+    PagerViewIOS15Compat.applyScrollEnabled(scrollEnabled, to: collectionView)
+  }
+
+  private func applyOverdrag(_ overdrag: Bool) {
+    collectionView?.bounces = overdrag
+    // iOS 15 only, see PagerViewIOS15Compat.swift (delete together with the iOS 15 support).
+    PagerViewIOS15Compat.applyOverdrag(overdrag, to: collectionView)
+  }
+
   var body: some View {
     GeometryReader { proxy in
       TabView(selection: $props.currentPage) {
@@ -39,8 +51,8 @@ struct PagerView: View {
       .environment(\.layoutDirection, props.layoutDirection.converted)
       .introspect(.tabView(style: .page), on: .iOS(.v14...)) { collectionView in
         self.collectionView = collectionView
-        collectionView.bounces = props.overdrag
-        collectionView.isScrollEnabled = props.scrollEnabled
+        applyOverdrag(props.overdrag)
+        applyScrollEnabled(props.scrollEnabled)
         collectionView.keyboardDismissMode = props.keyboardDismissMode
         collectionView.showsVerticalScrollIndicator = false
         collectionView.showsHorizontalScrollIndicator = false
@@ -70,8 +82,8 @@ struct PagerView: View {
       // Apply initial prop values that .onChange won't catch
       // (.onChange only fires on changes, not on initial values)
       DispatchQueue.main.async {
-        collectionView?.isScrollEnabled = props.scrollEnabled
-        collectionView?.bounces = props.overdrag
+        applyScrollEnabled(props.scrollEnabled)
+        applyOverdrag(props.overdrag)
       }
 
       // `onChange` does not fire for the initial `currentPage` value. Emit the
@@ -91,10 +103,10 @@ struct PagerView: View {
       delegate?.onPageSelected(position: newValue)
     }
     .onChange(of: props.scrollEnabled) { newValue in
-      collectionView?.isScrollEnabled = newValue
+      applyScrollEnabled(newValue)
     }
     .onChange(of: props.overdrag) { newValue in
-      collectionView?.bounces = newValue
+      applyOverdrag(newValue)
     }
     .onChange(of: props.keyboardDismissMode) { newValue in
       collectionView?.keyboardDismissMode = newValue

ios/PagerViewIOS15Compat.swift

@@ -0,0 +1,63 @@
+import UIKit
+
+/// Workarounds for the SwiftUI paged `TabView` on iOS 15.
+///
+/// On iOS 15 SwiftUI implements `.tabViewStyle(.page)` with a compositional layout that pages
+/// orthogonally: the horizontal paging is performed by an embedded `UIScrollView` subview of the
+/// collection view (private class `_UICollectionViewOrthogonalScrollerEmbeddedScrollView`), while
+/// the collection view itself only scrolls vertically. Because `PagerView` can only toggle the
+/// collection view, on iOS 15 `scrollEnabled={false}` / `overdrag={false}` never reached the view
+/// that actually handles the swipe.
+///
+/// On iOS 16 and later the collection view itself is the pager, so none of this is needed — the
+/// `#available` checks below make every function in here a no-op on those versions.
+///
+/// - Note: Delete this file together with the two `PagerViewIOS15Compat` calls in `PagerView.swift`
+///   once the minimum supported iOS version is 16.
+enum PagerViewIOS15Compat {
+  /// Mirrors `scrollEnabled` onto the scroll views SwiftUI embedded in the paging collection view.
+  static func applyScrollEnabled(_ scrollEnabled: Bool, to collectionView: UICollectionView?) {
+    if #available(iOS 16, *) {
+      return
+    }
+
+    pagingScrollViews(in: collectionView).forEach { $0.isScrollEnabled = scrollEnabled }
+  }
+
+  /// Mirrors `overdrag` onto the scroll views SwiftUI embedded in the paging collection view.
+  static func applyOverdrag(_ overdrag: Bool, to collectionView: UICollectionView?) {
+    if #available(iOS 16, *) {
+      return
+    }
+
+    pagingScrollViews(in: collectionView).forEach { $0.bounces = overdrag }
+  }
+
+  /// Scroll views that SwiftUI embedded in the paging collection view.
+  ///
+  /// Scroll views that belong to the pages' React Native content live inside the paging cells, so
+  /// the traversal stops at cell boundaries and never touches the user's own scroll views.
+  private static func pagingScrollViews(in collectionView: UICollectionView?) -> [UIScrollView] {
+    guard let collectionView else { return [] }
+
+    return collectPagingScrollViews(in: collectionView)
+  }
+
+  private static func collectPagingScrollViews(in view: UIView) -> [UIScrollView] {
+    var scrollViews: [UIScrollView] = []
+
+    for subview in view.subviews {
+      if subview is UICollectionViewCell {
+        continue
+      }
+
+      if let scrollView = subview as? UIScrollView {
+        scrollViews.append(scrollView)
+      }
+
+      scrollViews.append(contentsOf: collectPagingScrollViews(in: subview))
+    }
+
+    return scrollViews
+  }
+}