#188: Add support to swiping to dismiss keyboard for UIKitBackend

Sources/AppKitBackend/AppKitBackend.swift

@@ -861,6 +861,8 @@ public final class AppKitBackend: AppBackend {
         return scrollView
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {}
+
     public func setScrollBarPresence(
         ofScrollContainer scrollView: Widget,
         hasVerticalScrollBar: Bool,

Sources/CursesBackend/CursesBackend.swift

@@ -84,6 +84,8 @@ public final class CursesBackend: AppBackend {
 
     public func setSpacing(ofHStack container: Widget, to spacing: Int) {}
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {}
+
     public func createTextView() -> Widget {
         let label = Label("")
         label.width = Dim.fill()

Sources/Gtk3Backend/Gtk3Backend.swift

@@ -539,6 +539,8 @@ public final class Gtk3Backend: AppBackend {
         return scrollView
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {}
+
     public func setScrollBarPresence(
         ofScrollContainer scrollView: Widget,
         hasVerticalScrollBar: Bool,

Sources/GtkBackend/GtkBackend.swift

@@ -503,6 +503,8 @@ public final class GtkBackend: AppBackend {
         return scrollView
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {}
+
     public func setScrollBarPresence(
         ofScrollContainer scrollView: Widget,
         hasVerticalScrollBar: Bool,

Sources/LVGLBackend/LVGLBackend.swift

@@ -156,6 +156,8 @@ public final class LVGLBackend: AppBackend {
         }
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {}
+
     public func createTextView() -> Widget {
         return Widget { parent in
             let label = LVLabel(with: parent)

Sources/QtBackend/QtBackend.swift

@@ -108,6 +108,8 @@ public struct QtBackend: AppBackend {
         }
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {}
+
     public func setSpacing(ofHStack widget: Widget, to spacing: Int) {
         (widget.layout as! QHBoxLayout).spacing = Int32(spacing)
     }

Sources/SwiftCrossUI/Backend/AppBackend.swift

@@ -193,7 +193,7 @@
     /// A default implementation is provided. It uses the backend's reported
     /// device class and looks up the text style in a lookup table derived
     /// from Apple's typography guidelines. See ``TextStyle/resolve(for:)``.
     @Sendable func resolveTextStyle(_ textStyle: Font.TextStyle) -> Font.TextStyle.Resolved
 
     /// Computes a window's environment based off the root environment. This may involve
     /// updating ``EnvironmentValues/windowScaleFactor`` etc.
@@ -264,6 +264,18 @@
 
     /// Creates a scrollable single-child container wrapping the given widget.
     func createScrollContainer(for child: Widget) -> Widget
+    /// Updates a scroll container with environment-specific values.
+    ///
+    /// This method is primarily used on iOS to apply environment changes
+    /// that affect the scroll view’s behavior, such as keyboard dismissal mode.
+    ///
+    /// - Parameters:
+    ///   - scrollView: The scroll container widget previously created by `createScrollContainer(for:)`.
+    ///   - environment: The current `EnvironmentValues` to apply.
+    func updateScrollContainer(
+        _ scrollView: Widget,
+        environment: EnvironmentValues
+    )
     /// Sets the presence of scroll bars along each axis of a scroll container.
     func setScrollBarPresence(
         ofScrollContainer scrollView: Widget,
@@ -741,6 +753,10 @@
         todo()
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {
+        todo()
+    }
+
     public func setScrollBarPresence(
         ofScrollContainer scrollView: Widget,
         hasVerticalScrollBar: Bool,

Sources/SwiftCrossUI/Environment/EnvironmentValues.swift

@@ -78,6 +78,9 @@ public struct EnvironmentValues {
     /// Whether user interaction is enabled. Set by ``View/disabled(_:)``.
     public var isEnabled: Bool
 
+    /// The way that scrollable content interacts with the software keyboard.
+    public var scrollDismissesKeyboardMode: ScrollDismissesKeyboardMode
+
     /// Called by view graph nodes when they resize due to an internal state
     /// change and end up changing size. Each view graph node sets its own
     /// handler when passing the environment on to its children, setting up
@@ -196,6 +199,7 @@ public struct EnvironmentValues {
         listStyle = .default
         toggleStyle = .button
         isEnabled = true
+        scrollDismissesKeyboardMode = .automatic
     }
 
     /// Returns a copy of the environment with the specified property set to the

Sources/SwiftCrossUI/Values/ScrollDismissesKeyboardMode.swift

@@ -0,0 +1,28 @@
+/// The ways that scrollable content can interact with the software keyboard.
+///
+/// Use this type in a call to the ``View/scrollDismissesKeyboard(_:)``
+/// modifier to specify the dismissal behavior of scrollable views.
+public enum ScrollDismissesKeyboardMode: Sendable {
+    /// Determine the mode automatically based on the surrounding context.
+    ///
+    /// Currently, this behaves the same as ``ScrollDismissesKeyboardMode/interactively``.
+    /// In the future, it may adapt dynamically based on the context, similar to how
+    /// SwiftUI's `.automatic` works (e.g., using `.interactively` in some views and
+    /// `.immediately` in others). Using this value avoids source-breaking changes later on.
+    case automatic
+
+    /// Dismiss the keyboard as soon as scrolling starts.
+    case immediately
+
+    /// Enable people to interactively dismiss the keyboard as part of the
+    /// scroll operation.
+    ///
+    /// The software keyboard's position tracks the gesture that drives the
+    /// scroll operation if the gesture crosses into the keyboard's area of the
+    /// display. People can dismiss the keyboard by scrolling it off the
+    /// display, or reverse the direction of the scroll to cancel the dismissal.
+    case interactively
+
+    /// Never dismiss the keyboard automatically as a result of scrolling.
+    case never
+}

Sources/SwiftCrossUI/Views/Modifiers/ScrollDismissesKeyboardModifier.swift

@@ -0,0 +1,41 @@
+extension View {
+    /// Configures the behavior in which scrollable content interacts with
+    /// the software keyboard.
+    ///
+    /// You use this modifier to customize how scrollable content interacts
+    /// with the software keyboard. For example, you can specify a value of
+    /// ``ScrollDismissesKeyboardMode/immediately`` to indicate that you
+    /// would like scrollable content to immediately dismiss the keyboard if
+    /// present when a scroll drag gesture begins.
+    ///
+    ///     @State private var text = ""
+    ///
+    ///     ScrollView {
+    ///         TextField("Prompt", text: $text)
+    ///         ForEach(0 ..< 50) { index in
+    ///             Text("\(index)")
+    ///                 .padding()
+    ///         }
+    ///     }
+    ///     .scrollDismissesKeyboard(.immediately)
+    ///
+    /// You can also use this modifier to customize the keyboard dismissal
+    /// behavior for other kinds of scrollable views, like a ``List`` or a
+    /// ``TextEditor``.
+    ///
+    /// By default, scrollable content dismisses the keyboard interactively as the user scrolls.
+    /// Pass a different value of ``ScrollDismissesKeyboardMode`` to change this behavior.
+    /// For example, use ``ScrollDismissesKeyboardMode/never`` to prevent the keyboard from
+    /// dismissing automatically. Note that ``TextEditor`` may still use a different
+    /// default to preserve expected editing behavior.
+    ///
+    /// - Parameter mode: The keyboard dismissal mode that scrollable content
+    ///   uses.
+    ///
+    /// - Returns: A view that uses the specified keyboard dismissal mode.
+    public func scrollDismissesKeyboard(_ mode: ScrollDismissesKeyboardMode) -> some View {
+        EnvironmentModifier(self) { environment in
+            environment.with(\.scrollDismissesKeyboardMode, mode)
+        }
+    }
+}

Sources/SwiftCrossUI/Views/ScrollView.swift

@@ -143,6 +143,7 @@ public struct ScrollView<Content: View>: TypeSafeView, View {
                 hasVerticalScrollBar: hasVerticalScrollBar,
                 hasHorizontalScrollBar: hasHorizontalScrollBar
             )
+            backend.updateScrollContainer(widget, environment: environment)
         } else {
             finalResult = childResult
         }

Sources/UIKitBackend/UIKitBackend+Container.swift

@@ -56,6 +56,21 @@ final class ScrollWidget: ContainerWidget {
         scrollView.showsVerticalScrollIndicator = hasVerticalScrollBar
         scrollView.showsHorizontalScrollIndicator = hasHorizontalScrollBar
     }
+
+    public func updateScrollContainer(environment: EnvironmentValues) {
+        #if os(iOS)
+            scrollView.keyboardDismissMode = switch environment.scrollDismissesKeyboardMode {
+                case .automatic:
+                    .interactive
+                case .immediately:
+                    .onDrag
+                case .interactively:
+                    .interactive
+                case .never:
+                    .none
+            }
+        #endif
+    }
 }
 
 extension UIKitBackend {
@@ -121,6 +136,11 @@ extension UIKitBackend {
         ScrollWidget(child: child)
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {
+        let scrollViewWidget = scrollView as! ScrollWidget
+        scrollViewWidget.updateScrollContainer(environment: environment)
+    }
+
     public func setScrollBarPresence(
         ofScrollContainer scrollView: Widget,
         hasVerticalScrollBar: Bool,

Sources/UIKitBackend/UIKitBackend+Control.swift

@@ -317,6 +317,18 @@ extension UIKitBackend {
             } else {
                 textEditorWidget.child.inputAccessoryView = nil
             }
+
+            textEditorWidget.child.alwaysBounceVertical = environment.scrollDismissesKeyboardMode != .never
+            textEditorWidget.child.keyboardDismissMode = switch environment.scrollDismissesKeyboardMode {
+                case .automatic:
+                    textEditorWidget.child.inputAccessoryView == nil ? .interactive : .interactiveWithAccessory
+                case .immediately:
+                    textEditorWidget.child.inputAccessoryView == nil ? .onDrag : .onDragWithAccessory
+                case .interactively:
+                    textEditorWidget.child.inputAccessoryView == nil ? .interactive : .interactiveWithAccessory
+                case .never:
+                    .none
+            }
         #endif
     }
 

Sources/WinUIBackend/WinUIBackend.swift

@@ -616,6 +616,8 @@ public final class WinUIBackend: AppBackend {
         return scrollViewer
     }
 
+    public func updateScrollContainer(_ scrollView: Widget, environment: EnvironmentValues) {}
+
     public func setScrollBarPresence(
         ofScrollContainer scrollView: Widget,
         hasVerticalScrollBar: Bool,