General documentation

[RWOverdijk]

This project seems to be really useful and I've been trying to understand how it works. Is there more documentation available? It might be because I'm new to swift/swiftui but I find it difficult to understand how this works based on the examples.

More specifically, I'm trying to implement one of the "app store" demo sliders, specifically the one for "featured". I end up still having two directions to scroll in and I can't seem to get it to align to the bottom of the screen because it's taking up the full height (I think that's the vertical scroll, which I don't need but also can't get rid of).

This is what I ended up with:

import SwiftUI
import ASCollectionView_SwiftUI
import URLImage

struct NearbyVenuesListView : View {
    @State var title = Lorem.title

    @State var venues = DataSource.apps()

    var body: some View
    {
        ASCollectionView(section: ASSection(
            id: 0,
            data: venues,
            dataID: \.self,
            onCellEvent: self.onCellEvent) { item, _ in
            AppViewFeature(app: item)
        })
        .layout(self.layout)
        .contentInsets(.init(top: 10, left: 0, bottom: 10, right: 0))
        .shouldAttemptToMaintainScrollPositionOnOrientationChange(maintainPosition: false)
    }

    func onCellEvent(_ event: CellEvent<AppModel>)
    {
        switch event
        {
        case let .onAppear(item):
            ASRemoteImageManager.shared.load(item.featureImageURL)
        case let .onDisappear(item):
            ASRemoteImageManager.shared.cancelLoad(for: item.featureImageURL)
        case let .prefetchForData(data):
            for item in data
            {
                ASRemoteImageManager.shared.load(item.featureImageURL)
            }
        case let .cancelPrefetchForData(data):
            for item in data
            {
                ASRemoteImageManager.shared.cancelLoad(for: item.featureImageURL)
            }
        }
    }
}

extension NearbyVenuesListView
{
    var layout: ASCollectionLayout<Int>
    {
        ASCollectionLayout(scrollDirection: .vertical, interSectionSpacing: 20)
        { sectionID in
            ASCollectionLayoutSection
            { environment in
                let columnsToFit = floor(environment.container.effectiveContentSize.width / 320)
                let item = NSCollectionLayoutItem(layoutSize: NSCollectionLayoutSize(
                                                    widthDimension: .fractionalWidth(1.0), heightDimension: .fractionalHeight(1.0)))

                let width = 0.8 / columnsToFit;

                let itemsGroup = NSCollectionLayoutGroup.vertical(
                    layoutSize: NSCollectionLayoutSize(
                        widthDimension: .fractionalWidth(width),
                        heightDimension: .fractionalHeight(0.3)),
                    subitem: item, count: 1)

                let section = NSCollectionLayoutSection(group: itemsGroup)
                section.interGroupSpacing = 20
                section.contentInsets = NSDirectionalEdgeInsets(top: 0, leading: 20, bottom: 0, trailing: 20)
                section.orthogonalScrollingBehavior = .groupPaging
                section.visibleItemsInvalidationHandler = { _, _, _ in } // If this isn't defined, there is a bug in UICVCompositional Layout that will fail to update sizes of cells

                return section
            }
        }
    }
}

struct NearbyVenuesListView_Previews: PreviewProvider {
    static var previews: some View {
        NearbyVenuesListView()
    }
}

And I want to move this to the bottom and have the rest be transparent:

TL;DR; I don't understand how this library works and I would really like some pointers.

I'm sorry if this already documented somewhere. I couldn't find it 😅

[apptekstudios]

You could use a SwiftUI .frame(height: xxx) modifier to limit the height of the collection view.

eg.

VStack {
   Spacer()
   ASCollectionView { ... }
      .frame(height: 100)
}

[apptekstudios]

This documentation is helpful for UICollectionView layouts: https://developer.apple.com/documentation/uikit/views_and_controls/collection_views/implementing_modern_collection_views

[RWOverdijk]

Thank you. I ended up using a frame, but I felt like it was wrong. Apparently it's not 😄