feat(replay): skip snapshot during view controller transitions

CHANGELOG.md

@@ -1,5 +1,7 @@
 ## Next
 
+- fix: skip capturing a snapshot during view controller transitions ([#265](https://github.com/PostHog/posthog-ios/pull/265))
+
 ## 3.15.7 - 2024-11-25
 
 - fix: detect and mask out system photo library and user photos ([#261](https://github.com/PostHog/posthog-ios/pull/261))

PostHog/Replay/PostHogReplayIntegration.swift

@@ -367,6 +367,11 @@
                 return nil
             }
 
+            // this will bail on interactive animations (e.g edge slide)
+            if isAnimatingTransition(window) {
+                return nil
+            }
+
             var maskableWidgets: [CGRect] = []
             var maskChildren = false
             findMaskableWidgets(window, window, &maskableWidgets, &maskChildren)
@@ -386,6 +391,22 @@
             return wireframe
         }
 
+        /// Check if window's root view controller is animating a transition
+        private func isAnimatingTransition(_ window: UIWindow) -> Bool {
+            guard let viewController = window.rootViewController else { return false }
+
+            return isAnimatingTransition(viewController)
+        }
+
+        // Recursively check if a view controller (or any of its children) is currently animating a transition
+        // During a transition, a UIViewControllerTransitionCoordinator is assigned to a UIViewController which controls the overall transition
+        private func isAnimatingTransition(_ viewController: UIViewController) -> Bool {
+            if let isAnimated = viewController.transitionCoordinator?.isAnimated {
+                return isAnimated
+            }
+            return viewController.children.contains(where: isAnimatingTransition)
+        }
+
         private func isAssetsImage(_ image: UIImage) -> Bool {
             // https://github.com/daydreamboy/lldb_scripts#9-pimage
             // do not mask if its an asset image, likely not PII anyway

PostHog/Replay/UIView+Util.swift

@@ -54,7 +54,11 @@
             let renderer = UIGraphicsImageRenderer(size: size, format: rendererFormat)
 
             let image = renderer.image { _ in
-                drawHierarchy(in: bounds, afterScreenUpdates: false)
+                // true for afterScreenUpdates so that we capture view *after* any pending animations are committed
+                // As a side effect, we need to pause view tracker temporarily to avoid recursive calls since this option will cause subviews to layout, which will then trigger another capture
+                ViewLayoutTracker.paused = true
+                drawHierarchy(in: bounds, afterScreenUpdates: true)
+                ViewLayoutTracker.paused = false
             }
 
             return image

PostHog/Replay/ViewLayoutTracker.swift

@@ -3,14 +3,17 @@
     import UIKit
 
     enum ViewLayoutTracker {
-        static var hasChanges = false
+        static var paused = false
+        private(set) static var hasChanges = false
         private static var hasSwizzled = false
 
         static func viewDidLayout(view _: UIView) {
+            guard !paused else { return }
             hasChanges = true
         }
 
         static func clear() {
+            guard !paused else { return }
             hasChanges = false
         }