From a2fe0dfb789a77309ca57b101d982419d3e72045 Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Mon, 25 Sep 2023 21:44:43 -0400
Subject: [PATCH] Avoid unnecessarily recreating avatar views in notifications
 cells

---
 ...nNotificationGroupCollectionViewCell.swift | 30 +++++++++++--------
 ...wNotificationGroupCollectionViewCell.swift | 28 ++++++++++-------
 2 files changed, 35 insertions(+), 23 deletions(-)

diff --git a/Tusker/Screens/Notifications/ActionNotificationGroupCollectionViewCell.swift b/Tusker/Screens/Notifications/ActionNotificationGroupCollectionViewCell.swift
index 5dd71732..5efea38e 100644
--- a/Tusker/Screens/Notifications/ActionNotificationGroupCollectionViewCell.swift
+++ b/Tusker/Screens/Notifications/ActionNotificationGroupCollectionViewCell.swift
@@ -139,20 +139,26 @@ class ActionNotificationGroupCollectionViewCell: UICollectionViewListCell {
             mastodonController.persistentContainer.account(for: $0.account.id)
         }
         
-        avatarStack.arrangedSubviews.forEach { $0.removeFromSuperview() }
-        for avatarURL in people.lazy.compactMap(\.avatar).prefix(10) {
-            let imageView = CachedImageView(cache: .avatars)
-            imageView.contentMode = .scaleAspectFill
-            imageView.layer.masksToBounds = true
-            imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
-            imageView.layer.cornerCurve = .continuous
-            avatarStack.addArrangedSubview(imageView)
+        let visibleAvatars = Array(people.lazy.compactMap(\.avatar).prefix(10))
+        for (index, avatarURL) in visibleAvatars.enumerated() {
+            let imageView: CachedImageView
+            if index < avatarStack.arrangedSubviews.count {
+                imageView = avatarStack.arrangedSubviews[index] as! CachedImageView
+            } else {
+                imageView = CachedImageView(cache: .avatars)
+                imageView.contentMode = .scaleAspectFill
+                imageView.layer.masksToBounds = true
+                imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
+                imageView.layer.cornerCurve = .continuous
+                avatarStack.addArrangedSubview(imageView)
+                imageView.widthAnchor.constraint(equalTo: imageView.heightAnchor).isActive = true
+            }
             imageView.update(for: avatarURL)
         }
-        NSLayoutConstraint.activate(avatarStack.arrangedSubviews.map {
-            $0.widthAnchor.constraint(equalTo: $0.heightAnchor)
-        })
-        
+        for imageView in avatarStack.arrangedSubviews.dropFirst(visibleAvatars.count) {
+            avatarStack.removeArrangedSubview(imageView)
+        }
+
         actionLabel.setEmojis(pairs: people.map { ($0.displayOrUserName, $0.emojis) }, identifier: group.id)
         
         // todo: use htmlconverter
diff --git a/Tusker/Screens/Notifications/FollowNotificationGroupCollectionViewCell.swift b/Tusker/Screens/Notifications/FollowNotificationGroupCollectionViewCell.swift
index 513849c7..849357c3 100644
--- a/Tusker/Screens/Notifications/FollowNotificationGroupCollectionViewCell.swift
+++ b/Tusker/Screens/Notifications/FollowNotificationGroupCollectionViewCell.swift
@@ -116,19 +116,25 @@ class FollowNotificationGroupCollectionViewCell: UICollectionViewListCell {
         }, identifier: group.id)
         updateTimestamp()
         
-        avatarStack.arrangedSubviews.forEach { $0.removeFromSuperview() }
-        for avatarURL in people.lazy.compactMap(\.avatar).prefix(10) {
-            let imageView = CachedImageView(cache: .avatars)
-            imageView.contentMode = .scaleAspectFill
-            imageView.layer.masksToBounds = true
-            imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
-            imageView.layer.cornerCurve = .continuous
+        let visibleAvatars = Array(people.lazy.compactMap(\.avatar).prefix(10))
+        for (index, avatarURL) in visibleAvatars.enumerated() {
+            let imageView: CachedImageView
+            if index < avatarStack.arrangedSubviews.count {
+                imageView = avatarStack.arrangedSubviews[index] as! CachedImageView
+            } else {
+                imageView = CachedImageView(cache: .avatars)
+                imageView.contentMode = .scaleAspectFill
+                imageView.layer.masksToBounds = true
+                imageView.layer.cornerRadius = Preferences.shared.avatarStyle.cornerRadiusFraction * 30
+                imageView.layer.cornerCurve = .continuous
+                avatarStack.addArrangedSubview(imageView)
+                imageView.widthAnchor.constraint(equalTo: imageView.heightAnchor).isActive = true
+            }
             imageView.update(for: avatarURL)
-            avatarStack.addArrangedSubview(imageView)
         }
-        NSLayoutConstraint.activate(avatarStack.arrangedSubviews.map {
-            $0.widthAnchor.constraint(equalTo: $0.heightAnchor)
-        })
+        for imageView in avatarStack.arrangedSubviews.dropFirst(visibleAvatars.count) {
+            avatarStack.removeArrangedSubview(imageView)
+        }
     }
     
     private func updateActionLabel(names: [NSAttributedString]) -> NSAttributedString {