Change collection view deselect on appear to happen alongside nav pop

Tusker/Screens/Account List/AccountListViewController.swift

@@ -8,13 +8,13 @@
 
 import UIKit
 
-class AccountListViewController: UIViewController {
+class AccountListViewController: UIViewController, CollectionViewController {
     typealias Item = String
     
     private let mastodonController: MastodonController
     private let accountIDs: [String]
     
-    private var collectionView: UICollectionView {
+    var collectionView: UICollectionView! {
         view as! UICollectionView
     }
     private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
@@ -61,9 +61,7 @@ class AccountListViewController: UIViewController {
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
         
-        collectionView.indexPathsForSelectedItems?.forEach {
+        clearSelectionOnAppear(animated: animated)
-            collectionView.deselectItem(at: $0, animated: true)
-        }
     }
 }
 

Tusker/Screens/Explore/ExploreViewController.swift

@@ -12,11 +12,11 @@ import Pachyderm
 import CoreData
 import WebURLFoundationExtras
 
-class ExploreViewController: UIViewController, UICollectionViewDelegate {
+class ExploreViewController: UIViewController, UICollectionViewDelegate, CollectionViewController {
 
     weak var mastodonController: MastodonController!
     
-    private var collectionView: UICollectionView!
+    var collectionView: UICollectionView!
     private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
     
     private(set) var resultsController: SearchResultsViewController!
@@ -95,15 +95,7 @@ class ExploreViewController: UIViewController, UICollectionViewDelegate {
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
         
-        // Can't use UICollectionViewController's builtin version of this because it requires
+        clearSelectionOnAppear(animated: animated)
-        // the collection view layout be passed into the constructor. Swipe actions for list collection views
-        // are created by passing a closure to the layout's configuration. This closure needs to capture
-        // `self`, so it can't be passed into the super constructor.
-        if let indexPaths = collectionView.indexPathsForSelectedItems {
-            for indexPath in indexPaths {
-                collectionView.deselectItem(at: indexPath, animated: true)
-            }
-        }
     }
     
     override func viewDidAppear(_ animated: Bool) {

Tusker/Screens/Profile/ProfileStatusesViewController.swift

@@ -10,7 +10,7 @@ import UIKit
 import Pachyderm
 import Combine
 
-class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionViewController {
+class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionViewController, CollectionViewController {
     
     weak var owner: ProfileViewController?
     let mastodonController: MastodonController
@@ -188,9 +188,7 @@ class ProfileStatusesViewController: UIViewController, TimelineLikeCollectionVie
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
         
-        collectionView.indexPathsForSelectedItems?.forEach {
+        clearSelectionOnAppear(animated: animated)
-            collectionView.deselectItem(at: $0, animated: true)
-        }
         
         Task {
             if case .notLoadedInitial = controller.state {

Tusker/Screens/Status Action Account List/StatusActionAccountListViewController.swift

@@ -9,7 +9,7 @@
 import UIKit
 import Pachyderm
 
-class StatusActionAccountListViewController: UIViewController {
+class StatusActionAccountListViewController: UIViewController, CollectionViewController {
     
     private let mastodonController: MastodonController
     private let actionType: ActionType
@@ -20,8 +20,8 @@ class StatusActionAccountListViewController: UIViewController {
     /// If `true`, a warning will be shown below the account list describing that the total favs/reblogs may be innacurate.
     var showInacurateCountWarning = false
     
-    private var collectionView: UICollectionView {
+    var collectionView: UICollectionView! {
-        view as! UICollectionView
+        view as? UICollectionView
     }
     private var dataSource: UICollectionViewDiffableDataSource<Section, Item>!
     
@@ -120,9 +120,7 @@ class StatusActionAccountListViewController: UIViewController {
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
         
-        collectionView.indexPathsForSelectedItems?.forEach {
+        clearSelectionOnAppear(animated: animated)
-            collectionView.deselectItem(at: $0, animated: true)
-        }
         
         if accountIDs == nil {
             Task {

Tusker/Screens/Timeline/TimelineViewController.swift

@@ -210,9 +210,7 @@ class TimelineViewController: UIViewController, TimelineLikeCollectionViewContro
     override func viewWillAppear(_ animated: Bool) {
         super.viewWillAppear(animated)
         
-        collectionView.indexPathsForSelectedItems?.forEach {
+        clearSelectionOnAppear(animated: animated)
-            collectionView.deselectItem(at: $0, animated: true)
-        }
         
         if case .notLoadedInitial = controller.state {
             if restoreState() {

Tusker/Screens/Utilities/CollectionViewController.swift

@@ -11,3 +11,23 @@ import UIKit
 protocol CollectionViewController: UIViewController {
     var collectionView: UICollectionView! { get }
 }
+
+extension CollectionViewController {
+    func clearSelectionOnAppear(animated: Bool) {
+        guard let indexPath = collectionView.indexPathsForSelectedItems?.first else {
+            return
+        }
+        if let transitionCoordinator {
+            transitionCoordinator.animate { context in
+                self.collectionView.deselectItem(at: indexPath, animated: true)
+            } completion: { context in
+                if context.isCancelled {
+                    self.collectionView.selectItem(at: indexPath, animated: false, scrollPosition: [] /* UICollectionViewScrollPositionNone */)
+                }
+            }
+            
+        } else {
+            collectionView.deselectItem(at: indexPath, animated: animated)
+        }
+    }
+}