Added Header Support to Gallery

Sources/CollectionVStack/CollectionVGrid+inits.swift

@@ -2,7 +2,7 @@ import SwiftUI
 
 // MARK: Collection
 
-public extension CollectionVGrid {
+public extension CollectionVGrid where Header == EmptyView {
 
     init(
         uniqueElements: Data,
@@ -33,7 +33,7 @@ public extension CollectionVGrid {
     }
 }
 
-public extension CollectionVGrid where Element: Identifiable, ID == Element.ID {
+public extension CollectionVGrid where Element: Identifiable, ID == Element.ID, Header == EmptyView {
 
     init(
         uniqueElements: Data,
@@ -64,7 +64,7 @@ public extension CollectionVGrid where Element: Identifiable, ID == Element.ID {
 
 // MARK: Count
 
-public extension CollectionVGrid where Data == [Element], Element == Int, ID == Int {
+public extension CollectionVGrid where Data == [Element], Element == Int, ID == Int, Header == EmptyView {
 
     init(
         count: Int,

Sources/CollectionVStack/CollectionVGrid+modifiers.swift

@@ -1,3 +1,5 @@
+import SwiftUI
+
 public extension CollectionVGrid {
 
     func onReachedBottomEdge(
@@ -24,6 +26,22 @@ public extension CollectionVGrid {
         copy(modifying: \.onCancelPrefetchingElements, to: action)
     }
 
+    func header<NewHeader: View>(@ViewBuilder _ headerProvider: @escaping () -> NewHeader) -> CollectionVGrid<Element, Data, ID, Content, NewHeader> {
+        CollectionVGrid<Element, Data, ID, Content, NewHeader>(
+            id: _id,
+            data: data,
+            layout: layout,
+            onReachedBottomEdge: onReachedBottomEdge,
+            onReachedBottomEdgeOffset: onReachedBottomEdgeOffset,
+            onReachedTopEdge: onReachedTopEdge,
+            onReachedTopEdgeOffset: onReachedTopEdgeOffset,
+            onPrefetchingElements: onPrefetchingElements,
+            onCancelPrefetchingElements: onCancelPrefetchingElements,
+            headerProvider: headerProvider,
+            viewProvider: viewProvider
+        )
+    }
+
     func proxy(_ proxy: CollectionVGridProxy) -> Self {
         copy(modifying: \.proxy, to: proxy)
     }

Sources/CollectionVStack/CollectionVGrid.swift

@@ -5,11 +5,12 @@ public struct CollectionVGrid<
     Element,
     Data: Collection,
     ID: Hashable,
-    Content: View
+    Content: View,
+    Header: View
 >: UIViewRepresentable where Data.Element == Element,
 Data.Index == Int {
 
-    public typealias UIViewType = UICollectionVGrid<Element, Data, ID, Content>
+    public typealias UIViewType = UICollectionVGrid<Element, Data, ID, Content, Header>
 
     let _id: KeyPath<Element, ID>
     let data: Data
@@ -21,9 +22,10 @@ Data.Index == Int {
     var onPrefetchingElements: ([Element]) -> Void
     var onCancelPrefetchingElements: ([Element]) -> Void
     var proxy: CollectionVGridProxy?
+    var headerProvider: (() -> Header)?
     let viewProvider: (Element, CollectionVGridLocation) -> Content
 
-    init(
+    public init(
         id: KeyPath<Element, ID>,
         data: Data,
         layout: CollectionVGridLayout,
@@ -33,6 +35,7 @@ Data.Index == Int {
         onReachedTopEdgeOffset: CollectionVGridEdgeOffset = .offset(0),
         onPrefetchingElements: @escaping ([Element]) -> Void = { _ in },
         onCancelPrefetchingElements: @escaping ([Element]) -> Void = { _ in },
+        headerProvider: (() -> Header)? = nil,
         @ViewBuilder viewProvider: @escaping (Element, CollectionVGridLocation) -> Content
     ) {
         self._id = id
@@ -44,6 +47,7 @@ Data.Index == Int {
         self.onReachedTopEdgeOffset = onReachedTopEdgeOffset
         self.onPrefetchingElements = onPrefetchingElements
         self.onCancelPrefetchingElements = onCancelPrefetchingElements
+        self.headerProvider = headerProvider
         self.viewProvider = viewProvider
     }
 
@@ -59,6 +63,7 @@ Data.Index == Int {
             onPrefetchingElements: onPrefetchingElements,
             onCancelPrefetchingElements: onCancelPrefetchingElements,
             proxy: proxy,
+            headerProvider: headerProvider,
             viewProvider: viewProvider
         )
     }

Sources/CollectionVStack/UICollectionVGrid.swift

@@ -24,7 +24,8 @@ public class UICollectionVGrid<
     Element,
     Data: Collection,
     ID: Hashable,
-    Content: View
+    Content: View,
+    Header: View
 >:
     UIView,
     _UICollectionVGrid,
@@ -50,6 +51,11 @@ public class UICollectionVGrid<
     private let onPrefetchingElements: ([Element]) -> Void
     private let onCancelPrefetchingElements: ([Element]) -> Void
     private let viewProvider: (Element, CollectionVGridLocation) -> Content
+    private let headerProvider: (() -> Header)?
+    private var headerSize: CGSize?
+
+    private let headerReuseIdentifier = "HostingCollectionViewHeader"
+
 
     // MARK: init
 
@@ -64,6 +70,7 @@ public class UICollectionVGrid<
         onPrefetchingElements: @escaping ([Element]) -> Void,
         onCancelPrefetchingElements: @escaping ([Element]) -> Void,
         proxy: CollectionVGridProxy?,
+        headerProvider: (() -> Header)?,
         viewProvider: @escaping (Element, CollectionVGridLocation) -> Content
     ) {
         self._id = id
@@ -78,6 +85,7 @@ public class UICollectionVGrid<
         self.onPrefetchingElements = onPrefetchingElements
         self.onCancelPrefetchingElements = onCancelPrefetchingElements
         self.onReachedEdgeStore = []
+        self.headerProvider = headerProvider
         self.viewProvider = viewProvider
 
         super.init(frame: .zero)
@@ -105,6 +113,11 @@ public class UICollectionVGrid<
             HostingCollectionViewCell<Content>.self,
             forCellWithReuseIdentifier: cellReuseIdentifier
         )
+        collectionView.register(
+            HostingCollectionViewCell<Header>.self,
+            forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader,
+            withReuseIdentifier: headerReuseIdentifier
+        )
         collectionView.dataSource = self
         collectionView.prefetchDataSource = self
         collectionView.delegate = self
@@ -129,6 +142,8 @@ public class UICollectionVGrid<
         super.layoutSubviews()
 
         itemSize = nil
+        headerSize = nil
+
         collectionView.performBatchUpdates {
             collectionView.flowLayout.invalidateLayout()
         }
@@ -172,6 +187,7 @@ public class UICollectionVGrid<
             layout = newLayout
 
             itemSize = nil
+            headerSize = nil
 
             collectionView.flowLayout.sectionInset = newLayout.insets.asUIEdgeInsets
             collectionView.flowLayout.minimumLineSpacing = newLayout.lineSpacing
@@ -205,6 +221,7 @@ public class UICollectionVGrid<
 
         collectionView.alpha = 0
         itemSize = nil
+        headerSize = nil
         collectionView.reloadData()
 
         UIView.animate(withDuration: 0.1) {
@@ -240,6 +257,27 @@ public class UICollectionVGrid<
         return cell
     }
 
+    public func collectionView(
+        _ collectionView: UICollectionView,
+        viewForSupplementaryElementOfKind kind: String,
+        at indexPath: IndexPath
+    ) -> UICollectionReusableView {
+        guard kind == UICollectionView.elementKindSectionHeader,
+              let headerProvider = headerProvider else {
+            return UICollectionReusableView()
+        }
+
+        let header = collectionView.dequeueReusableSupplementaryView(
+            ofKind: kind,
+            withReuseIdentifier: headerReuseIdentifier,
+            for: indexPath
+        ) as! HostingCollectionViewCell<Header>
+
+        header.setup(view: headerProvider())
+
+        return header
+    }
+
     // MARK: UICollectionViewDelegate
 
     // required for tvOS
@@ -283,6 +321,33 @@ public class UICollectionVGrid<
         }
     }
 
+    public func collectionView(
+        _ collectionView: UICollectionView,
+        layout collectionViewLayout: UICollectionViewLayout,
+        referenceSizeForHeaderInSection section: Int
+    ) -> CGSize {
+        guard headerProvider != nil else {
+            return .zero
+        }
+
+        if let headerSize {
+            return headerSize
+        } else {
+            let width = collectionView.bounds.width
+            let view = headerProvider!()
+            let hostingController = UIHostingController(rootView: view.frame(width: width))
+            hostingController.view.sizeToFit()
+
+            let size = CGSize(
+                width: width,
+                height: hostingController.view.bounds.height
+            )
+
+            headerSize = size
+            return size
+        }
+    }
+
     // MARK: UIScrollViewDelegate
 
     public func scrollViewDidScroll(_ scrollView: UIScrollView) {