Hello,
how should I perform two next two operations with UICompositionalLayout?
Scroll To Specific offset
Change layout of the item, I'm scrolling to.
Whenever I try to call collectionView.collectionViewLayout.invalidateLayout(), I get reset:
Content Offset of UICollectionView
The layout change of the item is not updated
Here is the example of the layout I try to use.
let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
heightDimension: .estimated(100))
let item = NSCollectionLayoutItem(layoutSize: itemSize)
item.edgeSpacing = NSCollectionLayoutEdgeSpacing(leading: nil, top: .fixed(8), trailing: nil, bottom: .fixed(8))
let groupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
heightDimension: .estimated(100))
let group = NSCollectionLayoutGroup.horizontal(layoutSize: groupSize, subitems: [item])
let section = NSCollectionLayoutSection(group: group)
return section
And here is the example of cell
class ReelTextCellView: UICollectionViewCell {
private var textView: UITextView!
private var infoHolderView: UIView!
private var copyButton: UIButton!
private var scrollView: UIScrollView!
private var heightConstraint: NSLayoutConstraint!
var isExpanded = false
override init(frame: CGRect) {
super.init(frame: .zero)
buildView()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func preferredLayoutAttributesFitting(_ layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
let attributes = super.preferredLayoutAttributesFitting(layoutAttributes)
attributes.frame.size = .init(width: contentView.frame.width, height: isExpanded ? 300 : 100)
return attributes
}
// Called with the cellWillAppear and manually for indexPathsForVisibleItems
func update(with appeareance: Appearance) {
isExpanded = appeareance.isExpanded
/// heightConstraint.constant = appeareance.isExpanded ? 300 : 100
}
private extension ReelTextCellView {
func buildView() {
infoHolderView = UIView()
contentView.addSubview(infoHolderView) {
contentView.bottomAnchor.constraint(equalTo: infoHolderView.bottomAnchor)
contentView.leadingAnchor.constraint(equalTo: infoHolderView.leadingAnchor)
contentView.trailingAnchor.constraint(equalTo: infoHolderView.trailingAnchor)
infoHolderView.heightAnchor.constraint(equalToConstant: 30)
}
let separatorView = UIView()
separatorView.backgroundColor = Assets.Colors.separator.color
infoHolderView.addSubview(separatorView) {
separatorView.topAnchor.constraint(equalTo: infoHolderView.topAnchor)
separatorView.leadingAnchor.constraint(equalTo: infoHolderView.leadingAnchor)
separatorView.trailingAnchor.constraint(equalTo: infoHolderView.trailingAnchor)
separatorView.heightAnchor.constraint(equalToConstant: 0.5)
}
textView = UITextView()
contentView.addSubview(textView) {
textView.topAnchor.constraint(equalTo: contentView.topAnchor)
textView.leadingAnchor.constraint(equalTo: contentView.leadingAnchor)
textView.trailingAnchor.constraint(equalTo: contentView.trailingAnchor)
textView.bottomAnchor.constraint(equalTo: infoHolderView.topAnchor)
}
}
}
