Use snapshot placeholder to fix empty screenshot when navigating back

ios/App/App/AppDelegate.swift

@@ -199,8 +199,12 @@ class AppDelegate: UIResponder, UIApplicationDelegate, UINavigationControllerDel
                 pathStack[pathStack.count - 1] = toVC.targetPath
             }
 
-            // Move shared webview to destination before pop completes
-            SharedWebViewController.instance.attach(to: toVC)
+            // Move shared webview to destination before pop completes, but leave a snapshot
+            // on the previous screen so the transition doesn't show a blank page.
+            SharedWebViewController.instance.attach(
+                to: toVC,
+                leavePlaceholderInPreviousParent: fromVC != nil
+            )
 
             // Trigger browser back so Reitit updates route-match while attached to destination
             if let webView = SharedWebViewController.instance.bridgeController.bridge?.webView,
@@ -211,11 +215,16 @@ class AppDelegate: UIResponder, UIApplicationDelegate, UINavigationControllerDel
                 // Fallback: ask JS to render without adding history
                 ignoreRoutePopCount += 1
             }
+
+            coordinator.animate(alongsideTransition: nil) { _ in
+                SharedWebViewController.instance.clearPlaceholder()
+            }
         }
     }
 
     func navigationController(_ navigationController: UINavigationController, didShow viewController: UIViewController, animated: Bool) {
         guard let current = viewController as? NativePageViewController else { return }
+        SharedWebViewController.instance.clearPlaceholder()
         SharedWebViewController.instance.attach(to: current)
         attachNavigationSwipeGesture()
         updateSidebarGestureAttachment(for: current)

ios/App/App/SharedWebViewController.swift

@@ -7,6 +7,7 @@
 //
 
 import Foundation
+import UIKit
 import Capacitor
 
 @objc class SharedWebViewController: NSObject {
@@ -19,11 +20,22 @@ import Capacitor
     }()
 
     private weak var currentParent: UIViewController?
+    private weak var placeholderView: UIView?
 
-    func attach(to parent: UIViewController) {
+    func attach(to parent: UIViewController, leavePlaceholderInPreviousParent: Bool = false) {
         let vc = bridgeController
         guard currentParent !== parent else { return }
 
+        if leavePlaceholderInPreviousParent,
+           let previous = currentParent,
+           placeholderView == nil,
+           let snapshot = vc.view.snapshotView(afterScreenUpdates: false) {
+            snapshot.frame = previous.view.bounds
+            snapshot.autoresizingMask = [.flexibleWidth, .flexibleHeight]
+            previous.view.addSubview(snapshot)
+            placeholderView = snapshot
+        }
+
         // Detach from previous parent
         if let previous = currentParent {
             vc.willMove(toParent: nil)
@@ -39,4 +51,9 @@ import Capacitor
         parent.view.addSubview(vc.view)
         vc.didMove(toParent: parent)
     }
+
+    func clearPlaceholder() {
+        placeholderView?.removeFromSuperview()
+        placeholderView = nil
+    }
 }