public override void ViewDidLoad() { base.ViewDidLoad(); //Calculate Cell Size for screen resolution CGSize CellSize = GetSize(); /* * Initialize the collectionview layout */ UICollectionViewFlowLayout layout = new UICollectionViewFlowLayout { SectionInset = new UIEdgeInsets(20, 20, 20, 20), MinimumInteritemSpacing = 1, MinimumLineSpacing = 10, ItemSize = CellSize //new SizeF(110, 110) }; /* * Initialize the CollectionViewSource and UICollectionView */ CollectionViewSource = new CollectionViewImageStackSource(); CollectionViewSource.ImageViewSize = new SizeF((float)CellSize.Width, (float)CellSize.Height); CollectionView = new UICollectionView(UIScreen.MainScreen.Bounds, layout); CollectionView.BackgroundColor = AppColors.LIGHT_TEAL; var longPressGesture = new UILongPressGestureRecognizer(gesture => { // Take action based on state switch (gesture.State) { case UIGestureRecognizerState.Began: var selectedIndexPath = CollectionView.IndexPathForItemAtPoint(gesture.LocationInView(View)); if (selectedIndexPath != null) { CollectionView.BeginInteractiveMovementForItem(selectedIndexPath); } break; case UIGestureRecognizerState.Changed: CollectionView.UpdateInteractiveMovement(gesture.LocationInView(View)); break; case UIGestureRecognizerState.Ended: CollectionView.EndInteractiveMovement(); break; default: CollectionView.CancelInteractiveMovement(); break; } }); // Add the custom recognizer to the collection view CollectionView.AddGestureRecognizer(longPressGesture); CollectionView.ShowsHorizontalScrollIndicator = true; CollectionView.RegisterClassForCell(typeof(UserCell2), UserCell2.CellID); CollectionView.ShowsHorizontalScrollIndicator = true; CollectionView.Source = CollectionViewSource; }