highlightPreviewForItemAt for Collection View not working at all

Question

nemecek_f OP

Created Sep ’24

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Hello,

I have collection view with context menu using contextMenuConfigurationForItemAt and I wanted to customize the preview, when user long presses and context menu is shown. Something maybe like in the Music app when you long press on an album it shows the album in bigger size...

I found some snippets online for highlightPreviewForItemAt and dismissalPreviewForItemAt but it just doesn't work. As soon as a implemented these delegate methods, nothing happens when I long press, not even the standard preview with context menu.

These two methods aren't being called at all. Do I need to do something else? Do I need the previewProvider when creating the context menu? It is my understanding that that is needed only when the item should also open further detail on tap - which is something I don't need and want.

Below is my relevant implementation:

private func shareMenuConfiguration(for itemAt: URL, indexPath: IndexPath) -> UIContextMenuConfiguration {
        let share = UIAction(title: "Share".localized(), image: UIImage(systemName: "square.and.arrow.up")) { [unowned self] _ in
            
            let shareVC = UIActivityViewController(activityItems: [itemAt], applicationActivities: nil)
            
            if let cell = collectionView.cellForItem(at: indexPath) {
                shareVC.popoverPresentationController?.sourceView = cell.contentView
                shareVC.popoverPresentationController?.sourceRect = cell.contentView.bounds
            }
            
            self.present(shareVC, animated: true)
        }
        
        return UIContextMenuConfiguration(identifier: nil, previewProvider: nil) { _ in
            UIMenu(title: "", children: [share])
        }
    }
    
    func collectionView(_ collectionView: UICollectionView, contextMenuConfiguration configuration: UIContextMenuConfiguration, highlightPreviewForItemAt indexPath: IndexPath) -> UITargetedPreview? {
        guard let item = datasource.itemIdentifier(for: indexPath), let cell = collectionView.cellForItem(at: indexPath) as? GalleryImageCell else {
            return nil
        }
        
        let parameters = UIPreviewParameters()
        let visibleRect = cell.contentView.bounds.insetBy(dx: 1/3, dy: 1/3)
        let visiblePath = UIBezierPath(roundedRect: visibleRect, cornerRadius: 4)
        parameters.visiblePath = visiblePath
        
        return UITargetedPreview(
            view: cell.contentView,
            parameters: parameters,
            target: .init(container: collectionView, center: collectionView.convert(cell.contentView.center, from: cell.contentView))
        )
    }
    
    func collectionView(_ collectionView: UICollectionView, contextMenuConfiguration configuration: UIContextMenuConfiguration, dismissalPreviewForItemAt indexPath: IndexPath) -> UITargetedPreview? {
        guard let item = datasource.itemIdentifier(for: indexPath), let cell = collectionView.cellForItem(at: indexPath) as? GalleryImageCell else {
            return nil
        }
        
        let parameters = UIPreviewParameters()
        let visibleRect = cell.contentView.bounds.insetBy(dx: 1/3, dy: 1/3)
        let visiblePath = UIBezierPath(roundedRect: visibleRect, cornerRadius: 4)
        parameters.visiblePath = visiblePath
        
        return UITargetedPreview(
            view: cell.contentView,
            parameters: parameters,
            target: .init(container: collectionView, center: collectionView.convert(cell.contentView.center, from: cell.contentView))
        )
    }

Thanks!

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