Xamarin.CommunityToolkit by Microsoft

<PackageReference Include="Xamarin.CommunityToolkit" Version="2.0.6" />

.NET API 366,512 bytes

 Grouping<TKey, TSubKey, TItem>

public class Grouping<TKey, TSubKey, TItem> : ObservableRangeCollection<TItem>
Grouping of items by key and subkey into ObservableRange
public IList<TItem> Items { get; }

Returns list of items in the grouping.

public TKey Key { get; }

Gets the key.

public TSubKey SubKey { get; }

Gets the subkey of the grouping

public Grouping(TKey key, TSubKey subkey, IEnumerable<TItem> items)

Initializes a new instance of the Grouping class.