Liquid Glass interactive sheets

Author: elaine-signal

Signal/Registration/UserInterface/RegistrationSplashViewController.swift

@@ -208,6 +208,8 @@ public class RegistrationSplashViewController: OWSViewController, OWSNavigationC
 
 private class RestoreOrTransferPickerController: StackSheetViewController {
 
+    override var placeOnGlassIfAvailable: Bool { false }
+
     private let setHasOldDeviceBlock: ((Bool) -> Void)
     init(setHasOldDeviceBlock: @escaping (Bool) -> Void) {
         self.setHasOldDeviceBlock = setHasOldDeviceBlock

Signal/src/ViewControllers/AppSettings/Linked Devices/LinkOrSyncPickerSheet.swift

@@ -14,8 +14,9 @@ class LinkOrSyncPickerSheet: StackSheetViewController {
         UIColor.Signal.groupedBackground
     }
 
+    private let hMargin: CGFloat = 20
     override var stackViewInsets: UIEdgeInsets {
-        UIEdgeInsets(top: 0, leading: 20, bottom: 24, trailing: 20)
+        UIEdgeInsets(top: 0, leading: hMargin, bottom: 24, trailing: hMargin)
     }
 
     private let didDismiss: () -> Void
@@ -73,8 +74,8 @@ class LinkOrSyncPickerSheet: StackSheetViewController {
             }
         )
 
-        view.addSubview(closeButton)
-        closeButton.autoPinEdge(toSuperviewMargin: .trailing)
+        contentView.addSubview(closeButton)
+        closeButton.autoPinEdge(toSuperviewEdge: .trailing, withInset: hMargin)
         closeButton.autoAlignAxis(.horizontal, toSameAxisOf: titleLabel)
         closeButton.autoSetDimensions(to: .square(28))
 

SignalUI/ViewControllers/InteractiveSheetViewController.swift

@@ -63,6 +63,18 @@ open class InteractiveSheetViewController: OWSViewController {
     open var sheetBackgroundColor: UIColor { Theme.actionSheetBackgroundColor }
     open var handleBackgroundColor: UIColor { Theme.tableView2PresentedSeparatorColor }
 
+    /// Override to `true` to make the content appear on a glass background on
+    /// iOS 26 and later. `sheetBackgroundColor` will be ignored when on glass,
+    /// but still be sure to set it for devices running iOS 18 and older.
+    open var placeOnGlassIfAvailable: Bool { false }
+    private var isOnGlass: Bool {
+        if #available(iOS 26, *), FeatureFlags.iOS26SDKIsAvailable {
+            placeOnGlassIfAvailable
+        } else {
+            false
+        }
+    }
+
     public weak var externalBackdropView: UIView?
     private lazy var _internalBackdropView = UIView()
     public var backdropView: UIView? { externalBackdropView ?? _internalBackdropView }
@@ -154,7 +166,8 @@ open class InteractiveSheetViewController: OWSViewController {
         view.addSubview(sheetContainerView)
         sheetCurrentOffsetConstraint = sheetContainerView.autoPinEdge(toSuperviewEdge: .bottom)
         sheetContainerView.autoHCenterInSuperview()
-        sheetContainerView.backgroundColor = sheetBackgroundColor
+
+        let margin: CGFloat = isOnGlass ? 8 : 0
 
         // Prefer to be full width, but don't exceed the maximum width
         sheetContainerView.autoSetDimension(.width, toSize: maxWidth, relation: .lessThanOrEqual)
@@ -165,7 +178,12 @@ open class InteractiveSheetViewController: OWSViewController {
         }
 
         sheetContainerContentView.addSubview(sheetStackView)
-        sheetStackView.autoPinEdgesToSuperviewEdges()
+        sheetStackView.autoPinEdgesToSuperviewEdges(with: .init(
+            top: 0,
+            left: margin,
+            bottom: margin,
+            right: margin
+        ))
 
         contentView.preservesSuperviewLayoutMargins = true
         sheetStackView.addArrangedSubview(contentView)
@@ -187,6 +205,18 @@ open class InteractiveSheetViewController: OWSViewController {
 
         // Setup handle for interactive dismissal / resizing
         setupInteractiveSizing()
+
+        if #available(iOS 26.0, *), isOnGlass {
+#if compiler(>=6.2)
+            sheetContainerView.backgroundColor = .clear
+            let glassBackground = UIVisualEffectView(effect: UIGlassEffect(style: .regular))
+            sheetContainerView.insertSubview(glassBackground, at: 0)
+            glassBackground.autoPinEdges(toEdgesOf: sheetStackView)
+            glassBackground.cornerConfiguration = .uniformCorners(radius: .containerConcentric(minimum: 20))
+#endif
+        } else {
+            sheetContainerView.backgroundColor = sheetBackgroundColor
+        }
     }
 
     open override func viewDidDisappear(_ animated: Bool) {
@@ -198,7 +228,11 @@ open class InteractiveSheetViewController: OWSViewController {
         super.themeDidChange()
 
         handle.backgroundColor = handleBackgroundColor
-        sheetContainerView.backgroundColor = sheetBackgroundColor
+        sheetContainerView.backgroundColor = if isOnGlass {
+            .clear
+        } else {
+            sheetBackgroundColor
+        }
     }
 
     @objc
@@ -482,7 +516,17 @@ open class InteractiveSheetViewController: OWSViewController {
 
             // Add resistance above the max preferred height
             if newHeight > maxHeight {
-                newHeight = maxHeight + (newHeight - maxHeight) / resistanceDivisor
+                if isOnGlass {
+                    // Doing a transform keeps the glass background the same
+                    // height and prevents its concentric corners from shirking
+                    // as they get farther from the edges of the screen.
+                    sheetContainerView.transform = .translate(.init(x: 0, y: (maxHeight - newHeight) / resistanceDivisor))
+                    newHeight = maxHeight
+                } else {
+                    // When not on glass, we want the bottom of the sheet to
+                    // extend to the bottom of the screen, so don't transform.
+                    newHeight = maxHeight + (newHeight - maxHeight) / resistanceDivisor
+                }
             }
 
             // Don't go past the max allowed height
@@ -576,6 +620,7 @@ open class InteractiveSheetViewController: OWSViewController {
 
             sheetPanDelegate?.sheetPanDecelerationDidBegin()
             self.animate {
+                self.sheetContainerView.transform = .identity
                 self.sheetCurrentOffsetConstraint?.constant = finalOffset
                 self.sheetCurrentHeightConstraint.constant = finalHeight
                 self.view.layoutIfNeeded()

SignalUI/ViewControllers/StackSheetViewController.swift

@@ -19,6 +19,8 @@ open class StackSheetViewController: InteractiveSheetViewController {
         UIColor.Signal.groupedBackground
     }
 
+    open override var placeOnGlassIfAvailable: Bool { true }
+
     private lazy var preferredHeight: CGFloat = self.maximumAllowedHeight()
     open override func maximumPreferredHeight() -> CGFloat {
         min(self.preferredHeight, self.maximumAllowedHeight())