New infinite scroll iOS18

theleftbit · Sep 29, 2024 · 573dfda · 573dfda
1 parent 9193cad
commit 573dfda
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Showing 2 changed files with 65 additions and 56 deletions.
diff --git a/Sources/BSWInterfaceKit/SwiftUI/DataSource/InfiniteScrollingDataSource.swift b/Sources/BSWInterfaceKit/SwiftUI/DataSource/InfiniteScrollingDataSource.swift
@@ -7,7 +7,7 @@ import SwiftUI
 @MainActor
 open class InfiniteScrollingDataSource<ListItem: Identifiable & Sendable>: ObservableObject {
 
-    @Published public private(set) var items = [ListItem]()
+    @Published public var items = [ListItem]()
     @Published public private(set) var state: State
     @Published public var paginationError: Error?
     private var itemFetcher: ItemFetcher
@@ -66,17 +66,6 @@ open class InfiniteScrollingDataSource<ListItem: Identifiable & Sendable>: Obser
         try await loadMoreContent()
     }
 
-    /// This is a workaround for paging glitches found on iOS 17 and above.
-    /// As all workarouds, it's an indicator of a poor design that must be fixed ASAP.
-    public func ___update(items: [ListItem]? = nil, state: State? = nil) {
-        if let items {
-            self.items = items
-        }
-        if let state {
-            self.state = state
-        }
-    }
-
     /// MARK: Private
 
     @MainActor

diff --git a/Sources/BSWInterfaceKit/SwiftUI/Views/InfiniteVerticalScrollView.swift b/Sources/BSWInterfaceKit/SwiftUI/Views/InfiniteVerticalScrollView.swift
@@ -7,10 +7,15 @@ import SwiftUI
     @State
     var items: [Item] = Item.createItems()
 
+    @Previewable
+    @State
+    var pleaseScrollTo: Item.ID? = nil
+
     NavigationStack {
         InfiniteVerticalScrollView(
             direction: .downwards,
             items: $items,
+            pleaseScrollTo: $pleaseScrollTo,
             nextPageFetcher: { _ in
                 try await Task.sleep(for: .seconds(2))
                 return (Item.createItems(), true)
@@ -35,29 +40,30 @@ import SwiftUI
     }
 }
 
-@available(iOS 17, macOS 14, *)
+@available(iOS 18, macOS 14, *)
 public struct InfiniteVerticalScrollView<Item: Identifiable & Sendable, ItemView: View>: View where Item.ID : Sendable {
 
-    public init(direction: Direction = .downwards,
-         alignment: HorizontalAlignment = .center,
-         spacing: CGFloat? = nil,
-         pinnedViews: PinnedScrollableViews = .init(),
-         items: Binding<[Item]>,
-         nextPageFetcher: @escaping NextPageFetcher,
-         @ViewBuilder itemViewBuilder: @escaping ItemViewBuilder) {
-        self.alignment = alignment
-        self.spacing = spacing
-        self.pinnedViews = pinnedViews
-        self.direction = direction
-        self._items = items
-        self.nextPageFetcher = nextPageFetcher
-        self.itemViewBuilder = itemViewBuilder
+    public init(
+        direction: Direction = .downwards,
+        alignment: HorizontalAlignment = .center,
+        spacing: CGFloat? = nil,
+        pinnedViews: PinnedScrollableViews = .init(),
+        items: Binding<[Item]>,
+        pleaseScrollTo: Binding<Item.ID?>,
+        nextPageFetcher: @escaping NextPageFetcher,
+        @ViewBuilder itemViewBuilder: @escaping ItemViewBuilder) {
+            self.alignment = alignment
+            self.spacing = spacing
+            self.pinnedViews = pinnedViews
+            self.direction = direction
+            self._items = items
+            self._scrollPositionItemID = pleaseScrollTo
+            self.nextPageFetcher = nextPageFetcher
+            self.itemViewBuilder = itemViewBuilder
     }
 
     public enum Direction {
         case downwards
-
-        @available(iOS 18, macOS 15, *)
         case upwards
     }
 
@@ -77,12 +83,15 @@ public struct InfiniteVerticalScrollView<Item: Identifiable & Sendable, ItemView
     @State
     private var phase: Phase = .idle
 
-    @State
+    @Binding
     private var scrollPositionItemID: Item.ID?
 
     @State
     private var error: Swift.Error?
 
+    @State
+    private var pleaseScrollTo: Item.ID?
+
     enum Phase: Equatable {
         case idle
         case noMorePages
@@ -99,30 +108,38 @@ public struct InfiniteVerticalScrollView<Item: Identifiable & Sendable, ItemView
     }
 
     public var body: some View {
-        ScrollView(.vertical) {
-
-            if #available(iOS 18, macOS 15, *), direction == .upwards, phase.isPaging {
-                ProgressView()
-            }
+        ScrollViewReader { proxy in
+            ScrollView(.vertical) {
+                if direction == .upwards, phase.isPaging {
+                    ProgressView()
+                }
 
-            LazyVStack(alignment: alignment, spacing: spacing, pinnedViews: pinnedViews) {
-                ForEach(items) { item in
-                    itemViewBuilder(item)
-                        .id(item.id)
+                LazyVStack(alignment: alignment, spacing: spacing, pinnedViews: pinnedViews) {
+                    ForEach(items) { item in
+                        itemViewBuilder(item)
+                            .id(item.id)
+                    }
+                }
+                .scrollTargetLayout()
+
+                if direction == .downwards, phase.isPaging {
+                    ProgressView()
                 }
             }
-            .scrollTargetLayout()
-
-            if direction == .downwards, phase.isPaging {
-                ProgressView()
+            .onChange(of: pleaseScrollTo) { oldValue, newValue in
+                if let newValue {
+                    proxy.scrollTo(newValue, anchor: direction == .upwards ? .top : .bottom)
+                }
+                self.pleaseScrollTo = nil
             }
+            .scrollPosition(
+                id: $scrollPositionItemID,
+                anchor: (direction == .downwards) ? .bottom : .top
+            )
+            .defaultScrollAnchor((direction == .downwards) ? .top : .bottom)
+            .scrollDismissesKeyboard(.interactively)
         }
-        .scrollPosition(
-            id: $scrollPositionItemID,
-            anchor: (direction == .downwards) ? .bottom : .top
-        )
-        .defaultScrollAnchor((direction == .downwards) ? .top : .bottom)
-        .onChange(of: scrollPositionItemID) { _, newValue in
+        .onChange(of: scrollPositionItemID) { oldValue, newValue in
             if let newValue, newValue == anchorItemID, phase == .idle {
                 self.phase = .paging(fromItem: newValue)
             }
@@ -133,19 +150,22 @@ public struct InfiniteVerticalScrollView<Item: Identifiable & Sendable, ItemView
             }
             do {
                 let (newItems, areThereMorePages) = try await nextPageFetcher(itemID)
-                switch direction {
-                case .downwards:
-                    self.items.append(contentsOf: newItems)
-                case .upwards:
-                    self.items.insert(contentsOf: newItems, at: 0)
+                withAnimation {
+                    self.phase = areThereMorePages ? .idle : .noMorePages
+                } completion: {
+                    switch direction {
+                    case .downwards:
+                        self.items.append(contentsOf: newItems)
+                    case .upwards:
+                        self.items.insert(contentsOf: newItems, at: 0)
+                    }
+                    self.pleaseScrollTo = itemID
                 }
-                self.phase = areThereMorePages ? .idle : .noMorePages
             } catch {
                 self.phase = .idle
                 self.error = error
             }
         }
-        .errorAlert(error: $error)
     }
 
     private var anchorItemID: Item.ID? {