how to implement a uicollectionview that has multiple sections and subsections?

Question

The uicollectionview has n sections (say 1,2,3) that has m subsections (say 1.1,1.2 etc) which further branches into inner subsections (1.1.1, 1.1.2 etc) which finally has X no. of rows in it.

Answer 1

I've implemented this using UICollectionViewCompositionalLayout. Used the UICollectionViewCompositionalLayout { [self] (sectionNumber, environment) -> NSCollectionLayoutSection? in .... } closure to setup the layout items and group them vertically and horizontally to form the layout for the entire section.

For reference -

To create an individual item (H: 50, W: 50) -

let item = NSCollectionLayoutItem(layoutSize: NSCollectionLayoutSize(widthDimension: .absolute(50), heightDimension: .absolute(50)))

To create groups (Horizontal) -

let group = NSCollectionLayoutGroup.horizontal(layoutSize:
                                                                    NSCollectionLayoutSize(widthDimension:
                                                                            .absolute(item.layoutSize.widthDimension.dimension * CGFloat((data.count))),
                                                                                           heightDimension:  .estimated(50)), subitem: item, count: (data.count))

Group - vertical

 let subGroup = NSCollectionLayoutGroup.vertical(layoutSize:
                                                            NSCollectionLayoutSize(widthDimension:
                                                                    .absolute(CGFloat(width)),
                                                                                   heightDimension:
                                                                    .absolute(heightForIndividualItem * CGFloat(data.count))),
                                                        subitems: group)