Support using collection view safe area insets as cell layout margins

UI/NoorUI/Pager/PageViewController.swift

@@ -247,7 +247,7 @@ extension _PageViewController {
             self.element = element
             super.init(rootView: rootView)
             view.backgroundColor = .clear
-            _disableSafeAreaInsets()
+            _disableSafeArea = true
         }
 
         @available(*, unavailable)

UI/UIx/SwiftUI/CollectionView/CollectionView.swift

@@ -37,6 +37,7 @@ public struct CollectionView<
             configure: configure,
             content: content,
             isPagingEnabled: isPagingEnabled,
+            usesCollectionViewSafeAreaForCellLayoutMargins: usesCollectionViewSafeAreaForCellLayoutMargins,
             scrollAnchorId: scrollAnchorId,
             scrollAnchor: scrollAnchor
         )
@@ -64,6 +65,12 @@ public struct CollectionView<
         }
     }
 
+    public func usesCollectionViewSafeAreaForCellLayoutMargins(_ flag: Bool) -> Self {
+        mutateSelf {
+            $0.usesCollectionViewSafeAreaForCellLayoutMargins = flag
+        }
+    }
+
     // MARK: Private
 
     private let layout: UICollectionViewLayout
@@ -72,6 +79,7 @@ public struct CollectionView<
     private var configure: ((UICollectionView) -> Void)?
 
     private var isPagingEnabled: Bool = false
+    private var usesCollectionViewSafeAreaForCellLayoutMargins: Bool = false
 
     private var scrollAnchorId: Binding<Item.ID>?
     private var scrollAnchor: ScrollAnchor = .center
@@ -92,6 +100,7 @@ private struct CollectionViewBody<
     let content: (SectionId, Item) -> ItemContent
 
     let isPagingEnabled: Bool
+    let usesCollectionViewSafeAreaForCellLayoutMargins: Bool
 
     let scrollAnchorId: Binding<Item.ID>?
     let scrollAnchor: ScrollAnchor
@@ -123,6 +132,8 @@ private struct CollectionViewBody<
 
         viewController.dataSource?.sections = sections
 
+        viewController.usesCollectionViewSafeAreaForCellLayoutMargins = usesCollectionViewSafeAreaForCellLayoutMargins
+
         viewController.scroller.isPagingEnabled = isPagingEnabled
         viewController.scroller.onScrollAnchorIdUpdated = {
             scrollAnchorId?.wrappedValue = $0

UI/UIx/SwiftUI/CollectionView/CollectionViewController.swift

@@ -39,12 +39,29 @@ final class CollectionViewController<
     let collectionView: UICollectionView
     lazy var scroller = CollectionViewScroller<SectionId, Item>(collectionView: collectionView)
 
+    var usesCollectionViewSafeAreaForCellLayoutMargins = true {
+        didSet {
+            if usesCollectionViewSafeAreaForCellLayoutMargins != oldValue {
+                updateLayoutMarginsForVisibleCells()
+            }
+        }
+    }
+
     var dataSource: CollectionViewDataSource<SectionId, Item>? {
         didSet {
             scroller.dataSource = dataSource
         }
     }
 
+    override func viewSafeAreaInsetsDidChange() {
+        super.viewSafeAreaInsetsDidChange()
+        updateLayoutMarginsForVisibleCells()
+    }
+
+    override func loadView() {
+        view = collectionView
+    }
+
     override func viewIsAppearing(_ animated: Bool) {
         super.viewIsAppearing(animated)
         scroller.scrollToInitialItemIfNeeded()
@@ -63,15 +80,26 @@ final class CollectionViewController<
     // MARK: - Cell Lifecycle
 
     func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
-        (cell as? CellType)?.cellWillDisplay(animated: false)
+        guard let typedCell = cell as? CellType else {
+            return
+        }
+        typedCell.updateLayoutMargins(
+            usesCollectionViewSafeAreaForCellLayoutMargins: usesCollectionViewSafeAreaForCellLayoutMargins,
+            collectionViewSafeAreaInsets: view.safeAreaInsets
+        )
+
+        typedCell.cellWillDisplay(animated: false)
     }
 
     func collectionView(
         _ collectionView: UICollectionView,
         didEndDisplaying cell: UICollectionViewCell,
         forItemAt indexPath: IndexPath
     ) {
-        (cell as? CellType)?.cellDidEndDisplaying(animated: false)
+        guard let typedCell = cell as? CellType else {
+            return
+        }
+        typedCell.cellDidEndDisplaying(animated: false)
     }
 
     // MARK: - Paging
@@ -104,10 +132,6 @@ final class CollectionViewController<
         scroller.endInteractiveScrolling()
     }
 
-    override func loadView() {
-        view = collectionView
-    }
-
     // MARK: Private
 
     private func setUpDataSource(content: @escaping (SectionId, Item) -> ItemContent) {
@@ -129,7 +153,21 @@ final class CollectionViewController<
             let cell = collectionView.dequeueReusableCell(CellType.self, for: indexPath)
             cell.configure(content: content(section.id, item), dataId: itemId)
 
+            cell.updateLayoutMargins(
+                usesCollectionViewSafeAreaForCellLayoutMargins: usesCollectionViewSafeAreaForCellLayoutMargins,
+                collectionViewSafeAreaInsets: view.safeAreaInsets
+            )
+
             return cell
         }
     }
+
+    private func updateLayoutMarginsForVisibleCells() {
+        for cell in collectionView.visibleCells {
+            (cell as? CellType)?.updateLayoutMargins(
+                usesCollectionViewSafeAreaForCellLayoutMargins: usesCollectionViewSafeAreaForCellLayoutMargins,
+                collectionViewSafeAreaInsets: view.safeAreaInsets
+            )
+        }
+    }
 }

UI/UIx/SwiftUI/CollectionView/HostingCollectionViewCell.swift

@@ -10,6 +10,18 @@ import SwiftUI
 final class HostingCollectionViewCell<Content: View>: UICollectionViewCell {
     // MARK: Internal
 
+    override var safeAreaInsets: UIEdgeInsets {
+        .zero
+    }
+
+    func updateLayoutMargins(usesCollectionViewSafeAreaForCellLayoutMargins: Bool, collectionViewSafeAreaInsets: UIEdgeInsets) {
+        if usesCollectionViewSafeAreaForCellLayoutMargins {
+            cellLayoutMargins = .useCollectionViewSafeArea(collectionViewSafeAreaInsets)
+        } else {
+            cellLayoutMargins = .zero
+        }
+    }
+
     func configure(content: Content, dataId: AnyHashable) {
         self.dataId = dataId
         let content = EpoxySwiftUIHostingView<Content>.Content(rootView: content, dataID: dataId)
@@ -34,6 +46,12 @@ final class HostingCollectionViewCell<Content: View>: UICollectionViewCell {
     private var dataId: AnyHashable?
     private var hostingView: EpoxySwiftUIHostingView<Content>?
 
+    private var cellLayoutMargins: CollectionViewCellLayoutMargins = .zero {
+        didSet {
+            updateLayoutMarginsIfNeeded()
+        }
+    }
+
     private func setViewIfNeeded(view: EpoxySwiftUIHostingView<Content>) {
         guard hostingView == nil else {
             return
@@ -52,4 +70,18 @@ final class HostingCollectionViewCell<Content: View>: UICollectionViewCell {
             view.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),
         ])
     }
+
+    private func updateLayoutMarginsIfNeeded() {
+        switch cellLayoutMargins {
+        case .zero:
+            hostingView?.layoutMargins = .zero
+        case .useCollectionViewSafeArea(let insets):
+            hostingView?.layoutMargins = insets
+        }
+    }
+}
+
+private enum CollectionViewCellLayoutMargins {
+    case zero
+    case useCollectionViewSafeArea(_ safeArea: UIEdgeInsets)
 }