ViewModel.swift

extension ListViewController {
    @MainActor final class ViewModel {
        let palettes: [Palette]
        
        init(palettes: [Palette]) {
            self.palettes = palettes
        }
        
        func reloadContent(in dataSource: UICollectionViewDiffableDataSource<String, PaletteColor>) {
            var snapshot = NSDiffableDataSourceSnapshot<String, PaletteColor>()
            snapshot.appendSections(palettes.map(\.name))
            palettes.forEach({ palette in
                snapshot.appendItems(palette.colors, toSection: palette.name)
            })
            dataSource.apply(snapshot)
        }
    }
}