void ConfigureDataSource()
{
dataSource = new UICollectionViewDiffableDataSource <NSNumber, NSNumber> (collectionView, CellProviderHandler)
{
SupplementaryViewProvider = SupplementaryViewProviderHandler
};
// initial data
var snapshot = new NSDiffableDataSourceSnapshot <NSNumber, NSNumber> ();
var idOffset = 0;
var itemsPerSection = 18;
foreach (var section in SectionKind.AllSections)
{
snapshot.AppendSections(new [] { NSNumber.FromInt32(section.EnumValue) });
var items = Enumerable.Range(idOffset, itemsPerSection).Select(i => NSNumber.FromInt32(i)).ToArray();
snapshot.AppendItems(items);
idOffset += itemsPerSection;
}
dataSource.ApplySnapshot(snapshot, false);
UICollectionViewCell CellProviderHandler(UICollectionView collectionView, NSIndexPath indexPath, NSObject obj)
{
// Get a cell of the desired kind.
var cell = collectionView.DequeueReusableCell(TextCell.Key, indexPath) as TextCell;
// Populate the cell with our item description.
cell.Label.Text = $"{indexPath.Section}, {indexPath.Row}";
cell.ContentView.BackgroundColor = UIColorExtensions.CornflowerBlue;
cell.ContentView.Layer.BorderColor = UIColor.Black.CGColor;
cell.ContentView.Layer.BorderWidth = 1;
cell.ContentView.Layer.CornerRadius = 8;
cell.Label.TextAlignment = UITextAlignment.Center;
cell.Label.Font = UIFont.GetPreferredFontForTextStyle(UIFontTextStyle.Title1);
// Return the cell.
return(cell);
}
UICollectionReusableView SupplementaryViewProviderHandler(UICollectionView collectionView, string kind, NSIndexPath indexPath)
{
var sectionKind = SectionKind.GetSectionKind(indexPath.Section);
// Get a supplementary view of the desired kind.
var header = collectionView.DequeueReusableSupplementaryView(new NSString(kind),
TitleSupplementaryView.Key, indexPath) as TitleSupplementaryView;
// Populate the view with our section's description.
header.Label.Text = $".{sectionKind}";
// Return the view.
return(header);
}
}
// +-----------------------------------------------------+
// | +---------------------------------+ +-----------+ |
// | | | | | |
// | | | | | |
// | | | | 1 | |
// | | | | | |
// | | | | | |
// | | | +-----------+ |
// | | 0 | |
// | | | +-----------+ |
// | | | | | |
// | | | | | |
// | | | | 2 | |
// | | | | | |
// | | | | | |
// | +---------------------------------+ +-----------+ |
// +-----------------------------------------------------+
UICollectionViewLayout CreateLayout()
{
var config = new UICollectionViewCompositionalLayoutConfiguration {
InterSectionSpacing = 20
};
return(new UICollectionViewCompositionalLayout(SectionProviderHandler, config));
NSCollectionLayoutSection SectionProviderHandler(nint sectionIndex, INSCollectionLayoutEnvironment layoutEnvironment)
{
var sectionKind = SectionKind.GetSectionKind(sectionIndex);
var leadingItemSize = NSCollectionLayoutSize.Create(NSCollectionLayoutDimension.CreateFractionalWidth(.7f),
NSCollectionLayoutDimension.CreateFractionalHeight(1));
var leadingItem = NSCollectionLayoutItem.Create(leadingItemSize);
leadingItem.ContentInsets = new NSDirectionalEdgeInsets(10, 10, 10, 10);
var trailingItemSize = NSCollectionLayoutSize.Create(NSCollectionLayoutDimension.CreateFractionalWidth(1),
NSCollectionLayoutDimension.CreateFractionalHeight(.3f));
var trailingItem = NSCollectionLayoutItem.Create(trailingItemSize);
trailingItem.ContentInsets = new NSDirectionalEdgeInsets(10, 10, 10, 10);
var trailingGroupSize = NSCollectionLayoutSize.Create(NSCollectionLayoutDimension.CreateFractionalWidth(.3f),
NSCollectionLayoutDimension.CreateFractionalHeight(1));
var trailingGroup = NSCollectionLayoutGroup.CreateVertical(trailingGroupSize, trailingItem, 2);
var orthogonallyScrolls = sectionKind.GetOrthogonalScrollingBehavior() != UICollectionLayoutSectionOrthogonalScrollingBehavior.None;
var containerGroupFractionalWidth = orthogonallyScrolls ? .85f : 1;
var containerGroupSize = NSCollectionLayoutSize.Create(NSCollectionLayoutDimension.CreateFractionalWidth(containerGroupFractionalWidth),
NSCollectionLayoutDimension.CreateFractionalHeight(.4f));
var containerGroup = NSCollectionLayoutGroup.CreateHorizontal(containerGroupSize, leadingItem, trailingGroup);
var section = NSCollectionLayoutSection.Create(containerGroup);
section.OrthogonalScrollingBehavior = sectionKind.GetOrthogonalScrollingBehavior();
var sectionHeaderSize = NSCollectionLayoutSize.Create(NSCollectionLayoutDimension.CreateFractionalWidth(1),
NSCollectionLayoutDimension.CreateAbsolute(44));
var sectionHeader = NSCollectionLayoutBoundarySupplementaryItem.Create(sectionHeaderSize, headerElementKind, NSRectAlignment.Top);
section.BoundarySupplementaryItems = new [] { sectionHeader };
return(section);
}
}
