Remove extra backgroundFillView for the pop animation as can use the AlbumsViewController.view directly

Author: bivant

custom-transitions/Transitions/TransitionManager.swift

@@ -11,7 +11,6 @@ final class TransitionManager: NSObject, UIViewControllerAnimatedTransitioning {
 
     private let duration: TimeInterval
     private var operation = UINavigationController.Operation.push
-    private var popSnapshots = [UIViewController: UIView]()
 
     init(duration: TimeInterval) {
         self.duration = duration
@@ -64,8 +63,6 @@ private extension TransitionManager {
                 let detailsViewController = toViewController as? AlbumDetailViewController
             else { return }
 
-            popSnapshots[albumsViewController] = fromViewController.view.snapshotView(afterScreenUpdates: false)
-            
             presentViewController(detailsViewController, from: albumsViewController, with: context)
 
         case .pop:
@@ -140,17 +137,6 @@ private extension TransitionManager {
 
         let containerView = context.containerView
 
-        let backgroundFillView: UIView
-        if let snapshot = popSnapshots[toViewController] {
-            backgroundFillView = snapshot
-            backgroundFillView.frame = fromViewController.view.frame
-            popSnapshots[toViewController] = nil
-        } else {
-            backgroundFillView = UIView()
-            backgroundFillView.frame = fromViewController.view.frame
-            AlbumsViewController.setupBackgroundColor(for: backgroundFillView)
-        }
-        
         let snapshotContentView = UIView()
         snapshotContentView.backgroundColor = albumDetailRootView.backgroundColor
         snapshotContentView.frame = albumDetailRootView.frame
@@ -163,13 +149,10 @@ private extension TransitionManager {
         snapshotAlbumCoverImageView.layer.cornerRadius = albumDetailHeaderView.layer.cornerRadius
         snapshotAlbumCoverImageView.frame = containerView.convert(albumDetailHeaderView.albumCoverImageView.frame, from: albumDetailHeaderView)
 
-        containerView.addSubview(backgroundFillView)
         containerView.addSubview(toViewController.view)
         containerView.addSubview(snapshotContentView)
         containerView.addSubview(snapshotAlbumCoverImageView)
 
-        toViewController.view.isHidden = true
-        
         let animator = UIViewPropertyAnimator(duration: duration, curve: .easeInOut) {
             snapshotContentView.frame = containerView.convert(albumCell.contentView.frame, from: albumCell)
             snapshotContentView.backgroundColor = albumCell.contentView.backgroundColor
@@ -178,8 +161,6 @@ private extension TransitionManager {
         }
 
         animator.addCompletion { position in
-            toViewController.view.isHidden = false
-            backgroundFillView.removeFromSuperview()
             snapshotAlbumCoverImageView.removeFromSuperview()
             snapshotContentView.removeFromSuperview()
             context.completeTransition(position == .end)

custom-transitions/ViewController/AlbumsViewController.swift

@@ -45,29 +45,29 @@ class AlbumsViewController: UIViewController {
     override func viewDidAppear(_ animated: Bool) {
         super.viewDidAppear(animated)
     }
-    
-    static func setupBackgroundColor(for view: UIView) {
-        let gradient = CAGradientLayer()
-        gradient.frame = view.bounds
-        gradient.colors = [UIColor.backgroundColorGradient1 ?? .black, UIColor.backgroundColorGradient2 ?? .black].map { $0.cgColor }
-        gradient.startPoint = .init(x: 0.5, y: 0)
-        gradient.endPoint = .init(x: 0.5, y: 1)
-        gradient.locations = [0.5]
-        view.layer.insertSublayer(gradient, at: 0)
-    }
 }
 
 // MARK: - Setups
 
 private extension AlbumsViewController {
 
     func setupUI() {
-        Self.setupBackgroundColor(for: view)
+        setupBackgroundColor()
         setupHeaderView()
         setupCollectionView()
         setupPageControl()
     }
 
+    func setupBackgroundColor() {
+        let gradient = CAGradientLayer()
+        gradient.frame = view.bounds
+        gradient.colors = [UIColor.backgroundColorGradient1 ?? .black, UIColor.backgroundColorGradient2 ?? .black].map { $0.cgColor }
+        gradient.startPoint = .init(x: 0.5, y: 0)
+        gradient.endPoint = .init(x: 0.5, y: 1)
+        gradient.locations = [0.5]
+        view.layer.insertSublayer(gradient, at: 0)
+    }
+    
     func setupHeaderView() {
         let bandNameLabel = UILabel()
         bandNameLabel.font = .titleFont