Don't animate when dequeuing cells (#517)

https://block.atlassian.net/browse/UI-5081

We now force a non-animated layout before dequeuing a cell, to ensure
that any implicit animations that may occur are avoided. This avoids
issues where you may see an animation as a reused cell's changed state
is applied.

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ### Fixed
 
+- Fixed an issue where animations would occur when dequeuing / reusing cells. A layout is now forced without animation before presentation.
+
 ### Added
 
 ### Removed

ListableUI/Sources/ListView/ListView.Delegate.swift

@@ -140,6 +140,13 @@ extension ListView
             item.willDisplay(cell: cell, in: collectionView, for: indexPath)
 
             self.displayedItems[ObjectIdentifier(cell)] = item
+
+            UIView.performWithoutAnimation {
+                /// Force a layout of the cell before it is displayed, so that any implicit animations
+                /// are avoided. This ensures that cases like toggling a switch on and off are
+                /// not animated as the cell comes into view.
+                cell.layoutIfNeeded()
+            }
         }
 
         func collectionView(
@@ -175,6 +182,13 @@ extension ListView
             headerFooter.collectionViewWillDisplay(view: container)
 
             self.displayedSupplementaryItems[ObjectIdentifier(container)] = headerFooter
+
+            UIView.performWithoutAnimation {
+                /// Force a layout of the cell before it is displayed, so that any implicit animations
+                /// are avoided. This ensures that cases like toggling a switch on and off are
+                /// not animated as the cell comes into view.
+                container.layoutIfNeeded()
+            }
         }
 
         func collectionView(

ListableUI/Sources/ListView/ListView.VisibleContent.swift

@@ -24,16 +24,20 @@ extension ListView
             let removed = self.items.subtracting(newItems)
             let added = newItems.subtracting(self.items)
 
+            // Note: We set these values _before_ we invoke `setAndPerform`,
+            // incase `setAndPerform` causes an external callback to trigger
+            // an update, which could cause this method to be re-entrant.
+
+            self.items = newItems
+            self.headerFooters = newHeaderFooters
+
             removed.forEach {
                 $0.item.setAndPerform(isDisplayed: false)
             }
 
             added.forEach {
                 $0.item.setAndPerform(isDisplayed: true)
             }
-
-            self.items = newItems
-            self.headerFooters = newHeaderFooters
 
             // Inform any state reader callbacks of the changes.