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.

score 0 · Answer 1 · answered May 10 '22 at 05:54

0

Why not just use three collection views and three screens?

Tap on Section 1 creates second screen with collection view with sections Subsection 1 and Subsection 2.

Then tap on Subsection 1 creates third screen with collection view with sections Row 1, Row 1, Row 1, Row 1.

answered May 10 '22 at 05:54

12357665

36
5

No there should be no animations involved except horizontal and vertical scrolling. – Dracarys May 11 '22 at 13:47
@Dracarys If you need animations, then consider [new API](https://developer.apple.com/documentation/uikit/views_and_controls/collection_views/implementing_modern_collection_views): compositional layout and diffable datasource. – 12357665 May 11 '22 at 14:09

score 0 · Accepted Answer · answered May 30 '22 at 11:11

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)

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

2 Answers2