From c6e06fe9f3d761c419e8ded35bcb9b2be01b2caf Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Tue, 28 Jun 2022 17:27:41 -0700
Subject: [PATCH] Use SwiftUI for sheet presentation detents on iOS 16

---
 .../Compose/ComposeAttachmentsList.swift      | 51 ++++++++++++++++++-
 Tusker/Screens/Compose/ComposeUIState.swift   |  1 +
 2 files changed, 50 insertions(+), 2 deletions(-)

diff --git a/Tusker/Screens/Compose/ComposeAttachmentsList.swift b/Tusker/Screens/Compose/ComposeAttachmentsList.swift
index b83e39ab..0576f688 100644
--- a/Tusker/Screens/Compose/ComposeAttachmentsList.swift
+++ b/Tusker/Screens/Compose/ComposeAttachmentsList.swift
@@ -50,7 +50,7 @@ struct ComposeAttachmentsList: View {
             .disabled(!canAddAttachment)
             .foregroundColor(.blue)
             .frame(height: cellHeight / 2)
-            .popover(isPresented: $isShowingAssetPickerPopover, content: self.assetPickerPopover)
+            .sheetOrPopover(isPresented: $isShowingAssetPickerPopover, content: self.assetPickerPopover)
             .listRowInsets(EdgeInsets(top: cellPadding / 2, leading: cellPadding / 2, bottom: cellPadding / 2, trailing: cellPadding / 2))
             
             Button(action: self.createDrawing) {
@@ -134,14 +134,21 @@ struct ComposeAttachmentsList: View {
     private func assetPickerPopover() -> some View {
         ComposeAssetPicker(draft: draft, delegate: uiState.delegate?.assetPickerDelegate)
             .onDisappear {
+                // on iPadOS 16, this is necessary to dismiss the popover when collapsing from regular -> compact size class
+                // otherwise, the popover isn't visible but it's still "presented", so the sheet can't be shown
                 self.isShowingAssetPickerPopover = false
             }
+            // on iPadOS 16, this is necessary to show the dark color in the popover arrow
+            .background(Color(.systemBackground))
             .environment(\.colorScheme, .dark)
             .edgesIgnoringSafeArea(.bottom)
+            .withSheetDetentsIfAvailable()
     }
     
     private func addAttachment() {
-        if horizontalSizeClass == .regular {
+        if #available(iOS 16.0, *) {
+            isShowingAssetPickerPopover = true
+        } else if horizontalSizeClass == .regular {
             isShowingAssetPickerPopover = true
         } else {
             uiState.delegate?.presentAssetPickerSheet()
@@ -184,6 +191,7 @@ struct ComposeAttachmentsList: View {
 }
 
 fileprivate extension View {
+    @available(iOS, obsoleted: 15.0)
     @ViewBuilder
     func onDragWithPreviewIfAvailable<V>(_ data: @escaping () -> NSItemProvider, preview: () -> V) -> some View where V : View {
         if #available(iOS 15.0, *) {
@@ -192,6 +200,45 @@ fileprivate extension View {
             self.onDrag(data)
         }
     }
+    
+    @available(iOS, obsoleted: 16.0)
+    @ViewBuilder
+    func sheetOrPopover(isPresented: Binding<Bool>, @ViewBuilder content: @escaping () -> some View) -> some View {
+        if #available(iOS 16.0, *) {
+            self.modifier(SheetOrPopover(isPresented: isPresented, view: content))
+        } else {
+            self.popover(isPresented: isPresented, content: content)
+        }
+    }
+    
+    @available(iOS, obsoleted: 16.0)
+    @ViewBuilder
+    func withSheetDetentsIfAvailable() -> some View {
+        if #available(iOS 16.0, *) {
+            self
+                .presentationDetents([.medium, .large])
+                .presentationDragIndicator(.visible)
+        } else {
+            self
+        }
+    }
+}
+
+@available(iOS 16.0, *)
+struct SheetOrPopover<V: View>: ViewModifier {
+    @Binding var isPresented: Bool
+    @ViewBuilder let view: () -> V
+    
+    @Environment(\.horizontalSizeClass) var sizeClass
+    
+    func body(content: Content) -> some View {
+        let _ = print("isPresented: \(isPresented)")
+        if sizeClass == .compact {
+            content.sheet(isPresented: $isPresented, content: view)
+        } else {
+            content.popover(isPresented: $isPresented, content: view)
+        }
+    }
 }
 
 //struct ComposeAttachmentsList_Previews: PreviewProvider {
diff --git a/Tusker/Screens/Compose/ComposeUIState.swift b/Tusker/Screens/Compose/ComposeUIState.swift
index 0e038b73..4ff53ce5 100644
--- a/Tusker/Screens/Compose/ComposeUIState.swift
+++ b/Tusker/Screens/Compose/ComposeUIState.swift
@@ -12,6 +12,7 @@ protocol ComposeUIStateDelegate: AnyObject {
     var assetPickerDelegate: AssetPickerViewControllerDelegate? { get }
     
     func dismissCompose(mode: ComposeUIState.DismissMode)
+    // @available(iOS, obsoleted: 16.0)
     func presentAssetPickerSheet()
     func presentComposeDrawing()