UIKit sheet parent dismissals now dismiss both all children and the parent sheet itself

on AppKit its probably easier to let users handle this by just setting isPresented to false, as the implementation is quite different than on UIKit using windows instead of views. Maybe potential improvement later/in a different pr

Author: MiaKoring

Examples/Sources/WindowingExample/WindowingApp.swift

@@ -64,6 +64,7 @@ struct AlertDemo: View {
     }
 }
 
+// kind of a stress test for the dismiss action
 struct SheetDemo: View {
     @State var isPresented = false
     @State var isShortTermSheetPresented = false
@@ -85,7 +86,7 @@ struct SheetDemo: View {
             SheetBody()
                 .presentationDetents([.height(150), .medium, .large])
                 .presentationDragIndicatorVisibility(.visible)
-                .presentationBackground(.blue)
+                .presentationBackground(.green)
         }
         .sheet(isPresented: $isShortTermSheetPresented) {
             Text("I'm only here for 5s")
@@ -98,6 +99,7 @@ struct SheetDemo: View {
 
     struct SheetBody: View {
         @State var isPresented = false
+        @Environment(\.dismiss) var dismiss
 
         var body: some View {
             VStack {
@@ -107,12 +109,51 @@ struct SheetDemo: View {
                     isPresented = true
                     print("should get presented")
                 }
+                Button("Dismiss") {
+                    dismiss()
+                }
                 Spacer()
             }
             .sheet(isPresented: $isPresented) {
                 print("nested sheet dismissed")
             } content: {
+                NestedSheetBody(dismissParent: { dismiss() })
+            }
+        }
+
+        struct NestedSheetBody: View {
+            @Environment(\.dismiss) var dismiss
+            var dismissParent: () -> Void
+            @State var showNextChild = false
+
+            var body: some View {
                 Text("I'm nested. Its claustrophobic in here.")
+                Button("New Child Sheet") {
+                    showNextChild = true
+                }
+                .sheet(isPresented: $showNextChild) {
+                    DoubleNestedSheetBody(dismissParent: { dismiss() })
+                }
+                Button("dismiss parent sheet") {
+                    dismissParent()
+                }
+                Button("dismiss") {
+                    dismiss()
+                }
+            }
+        }
+        struct DoubleNestedSheetBody: View {
+            @Environment(\.dismiss) var dismiss
+            var dismissParent: () -> Void
+
+            var body: some View {
+                Text("I'm nested. Its claustrophobic in here.")
+                Button("dismiss parent sheet") {
+                    dismissParent()
+                }
+                Button("dismiss") {
+                    dismiss()
+                }
             }
         }
     }

Sources/SwiftCrossUI/Environment/Actions/DismissAction.swift

@@ -0,0 +1,70 @@
+/// An action that dismisses the current presentation context.
+///
+/// Use the `dismiss` environment value to get an instance of this action,
+/// then call it to dismiss the current sheet.
+///
+/// Example usage:
+/// ```swift
+/// struct SheetContentView: View {
+///     @Environment(\.dismiss) var dismiss
+///
+///     var body: some View {
+///         VStack {
+///             Text("Sheet Content")
+///             Button("Close") {
+///                 dismiss()
+///             }
+///         }
+///     }
+/// }
+/// ```
+@MainActor
+public struct DismissAction {
+    private let action: () -> Void
+
+    internal init(action: @escaping () -> Void) {
+        self.action = action
+    }
+
+    /// Dismisses the current presentation context.
+    public func callAsFunction() {
+        action()
+    }
+}
+
+/// Environment key for the dismiss action.
+private struct DismissActionKey: EnvironmentKey {
+    @MainActor
+    static var defaultValue: DismissAction {
+        DismissAction(action: {
+            #if DEBUG
+                print("warning: dismiss() called but no presentation context is available")
+            #endif
+        })
+    }
+}
+
+extension EnvironmentValues {
+    /// An action that dismisses the current presentation context.
+    ///
+    /// Use this environment value to get a dismiss action that can be called
+    /// to dismiss the current sheet, popover, or other presentation.
+    ///
+    /// Example:
+    /// ```swift
+    /// struct ContentView: View {
+    ///     @Environment(\.dismiss) var dismiss
+    ///
+    ///     var body: some View {
+    ///         Button("Close") {
+    ///             dismiss()
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    @MainActor
+    public var dismiss: DismissAction {
+        get { self[DismissActionKey.self] }
+        set { self[DismissActionKey.self] = newValue }
+    }
+}

Sources/SwiftCrossUI/Values/PresentationDragIndicatorVisibility.swift

@@ -1,3 +1,3 @@
-public enum PresentationDragIndicatorVisibility {
+public enum PresentationDragIndicatorVisibility: Sendable {
     case hidden, visible
 }

Sources/SwiftCrossUI/Views/Modifiers/SheetModifier.swift

@@ -73,10 +73,15 @@ struct SheetModifier<Content: View, SheetContent: View>: TypeSafeView {
         if isPresented.wrappedValue && children.sheet == nil {
             let sheet = backend.createSheet()
 
+            let dismissAction = DismissAction(action: { [isPresented] in
+                isPresented.wrappedValue = false
+            })
+            let sheetEnvironment = environment.with(\.dismiss, dismissAction)
+
             let dryRunResult = children.sheetContentNode.update(
                 with: sheetContent(),
                 proposedSize: sheet.size,
-                environment: environment,
+                environment: sheetEnvironment,
                 dryRun: true
             )
 
@@ -85,7 +90,7 @@ struct SheetModifier<Content: View, SheetContent: View>: TypeSafeView {
             let _ = children.sheetContentNode.update(
                 with: sheetContent(),
                 proposedSize: sheet.size,
-                environment: environment,
+                environment: sheetEnvironment,
                 dryRun: false
             )
 
@@ -95,7 +100,7 @@ struct SheetModifier<Content: View, SheetContent: View>: TypeSafeView {
                 onDismiss: handleDismiss
             )
 
-            // Apply presentation preferences to the sheet
+            // MARK: Sheet Presentation Preferences
             if let cornerRadius = preferences.presentationCornerRadius {
                 backend.setPresentationCornerRadius(of: sheet, to: cornerRadius)
             }

Sources/UIKitBackend/UIKitBackend+Sheet.swift

@@ -26,7 +26,15 @@ extension UIKitBackend {
     }
 
     public func dismissSheet(_ sheet: CustomSheet, window: UIWindow?) {
-        sheet.dismiss(animated: true)
+        // If this sheet has a presented view controller (nested sheet), dismiss it first
+        if let presentedVC = sheet.presentedViewController {
+            presentedVC.dismiss(animated: false) { [weak sheet] in
+                // After the nested sheet is dismissed, dismiss this sheet
+                sheet?.dismissProgrammatically()
+            }
+        } else {
+            sheet.dismissProgrammatically()
+        }
     }
 
     public func setPresentationDetents(of sheet: CustomSheet, to detents: [PresentationDetent]) {
@@ -110,12 +118,24 @@ public final class CustomSheet: UIViewController, SheetImplementation {
     }
 
     var onDismiss: (() -> Void)?
+    private var isDismissedProgrammatically = false
 
     public override func viewDidLoad() {
         super.viewDidLoad()
     }
 
+    func dismissProgrammatically() {
+        isDismissedProgrammatically = true
+        dismiss(animated: true)
+    }
+
     public override func viewDidDisappear(_ animated: Bool) {
-        onDismiss?()
+        super.viewDidDisappear(animated)
+
+        // Only call onDismiss if the sheet was dismissed by user interaction (swipe down, tap outside)
+        // not when dismissed programmatically via the dismiss action
+        if !isDismissedProgrammatically {
+            onDismiss?()
+        }
     }
 }