Ios swift - Double height cell in UICollectionView

AltynbekTanbayev
January 28, 2024
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0 votes
2 Answers

How can I implement such layout using UICollectionView in UIKit? I need to add a new cell which height is greater than height of normal cell. AFAIK all cells in one row of UICollectionView must have the same height.

Answers

you can set that specific cell size in the below way:

extension YourViewController: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        if indexPath.item == /*your desired cell index*/ {
            return CGSize(width: normalWidth, height: doubleSizeHeight)            
        } else {
            return CGSize(width: normalWidth, height: normalHeight)
        }
    }
}

I think UICollectionViewCompositionalLayout will fit this scenario. It supports complex collection UI, like waterfall, nested cells, etc. And based on your requirements, it could be:

//Defining sections
enum Section: Int, Hashable {
    case waterfall
    case normal
}

//And layouts for sections
let layout = UICollectionViewCompositionalLayout {
    (sectionIndex: Int, layoutEnvironment: NSCollectionLayoutEnvironment) -> NSCollectionLayoutSection? in
    guard let sectionKind = Section(rawValue: sectionIndex) else { return nil}

    let section: NSCollectionLayoutSection

    if sectionKind == .waterfall {
        let leadingItem = NSCollectionLayoutItem(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(0.7),
                                               heightDimension: .fractionalHeight(1.0)))
        leadingItem.contentInsets = NSDirectionalEdgeInsets(top: 10, leading: 10, bottom: 10, trailing: 10)

        let trailingItem = NSCollectionLayoutItem(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                               heightDimension: .fractionalHeight(0.3)))
        trailingItem.contentInsets = NSDirectionalEdgeInsets(top: 10, leading: 10, bottom: 10, trailing: 10)
        let trailingGroup = NSCollectionLayoutGroup.vertical(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(0.3),
                                               heightDimension: .fractionalHeight(1.0)),
            subitem: trailingItem, count: 2)

        let nestedGroup = NSCollectionLayoutGroup.horizontal(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                               heightDimension: .fractionalHeight(0.4)),
            subitems: [leadingItem, trailingGroup])
        section = NSCollectionLayoutSection(group: nestedGroup)

    } else {
        let leadingItem = NSCollectionLayoutItem(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(0.5),
                                               heightDimension: .fractionalHeight(1.0)))
        leadingItem.contentInsets = NSDirectionalEdgeInsets(top: 10, leading: 10, bottom: 10, trailing: 10)

        let trailingItem = NSCollectionLayoutItem(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(0.5),
                                               heightDimension: .fractionalHeight(1.0)))
        trailingItem.contentInsets = NSDirectionalEdgeInsets(top: 10, leading: 10, bottom: 10, trailing: 10)

        let nestedGroup = NSCollectionLayoutGroup.horizontal(
            layoutSize: NSCollectionLayoutSize(widthDimension: .fractionalWidth(1.0),
                                               heightDimension: .fractionalHeight(0.2)),
            subitems: [leadingItem, trailingItem])
        section = NSCollectionLayoutSection(group: nestedGroup)
    }

    return section
}

collectionView = UICollectionView(frame: view.bounds, collectionViewLayout: layout)

The following is an explanation of the layouts above (all with insets):

waterfall: A section that has (width: 1.0, height: 0.4) ratio with collectionView frame. It contains a leading cell item with (width: 0.7, height: 1.0). And a pair of trailing vertical cells with (width: 0.3, height: 1.0). Each cell in this group will have (width: 1.0, height: 0.3) to their group

normal: A section that has (width: 1.0, height 0.2) ratio with collectionView frame. The layout will present two cells and each cell will get 0.5 width of collectionView.

UPDATED: I used UICollectionViewDiffableDataSource, configured it is simple:

//A struct to represent cell data. Notice: it has to conform Hashable
struct CellData: Hashable {
    var title: String = ""
    var identifier: UUID = .init()

    init(_ title: String) {
        self.title = title
    }
}

//A dataSource represents collectionView data
var dataSource: UICollectionViewDiffableDataSource<Section, CellData>

Then append sections and items like you want:

//Simple text cell with a label
let cellRegistration = UICollectionView.CellRegistration<TextCell, CellData> { (cell, indexPath, identifier) in
    cell.label.text = identifier.title
    //Other configurations
}

dataSource = UICollectionViewDiffableDataSource<Section, CellData>(collectionView: collectionView, cellProvider: { collectionView, indexPath, item in
    collectionView.dequeueConfiguredReusableCell(using: cellRegistration, for: indexPath, item: item)
})

var snapshot = NSDiffableDataSourceSnapshot<Section, CellData>()
snapshot.appendSections([.waterfall])
let dummyWaterfallSection: [CellData] = [
    .init("1"),
    .init("2"),
    .init("3"),
]
snapshot.appendItems(dummyWaterfallSection, toSection: .waterfall)

snapshot.appendSections([.normal])
let dummyNormalSection: [CellData] = [
    .init("11"),
    .init("22"),
    .init("33"),
    .init("44"),
    .init("55"),
]
snapshot.appendItems(dummyNormalSection, toSection: .normal)

dataSource.apply(snapshot, animatingDifferences: false)

Output:

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Ios swift – Double height cell in UICollectionView

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