我有一个自写的库，带有
UICollectionViewCompositionalLayoutUICollectionViewCompositionalLayoutNewViewControllerNewViewController我的NewViewController代码：
import UIKit
import MyTestLibrary
class NewViewController: UIViewController {
let shopViewController = ShopViewController()
override func viewDidLoad() {
super.viewDidLoad()
shopViewController.createCollectionView()
view.addSubview(shopViewController.collectionView)
}
// some code to use only 2 cell
}
我的图书馆代码：
import UIKit
public class ShopViewController: UIViewController {
///` create collection view
public var collectionView: UICollectionView!
///` load data source from Section, Book files
public var dataSource: UICollectionViewDiffableDataSource<Section, Book>?
///` load data from JSON file
public let sections = Bundle.main.decode([Section].self, from: "appstore.json")
public override func viewDidLoad() {
super.viewDidLoad()
createCollectionView()
}
public func createCollectionView() {
collectionView = UICollectionView(
frame: view.bounds,
collectionViewLayout: createCompositionalLayout())
collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
collectionView.backgroundColor = .systemBackground
view.addSubview(collectionView)
///` register section header
collectionView.register(SectionHeader.self,
forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader,
withReuseIdentifier: SectionHeader.reuseIdentifier)
///` register cells
collectionView.register(FeaturedCell.self,
forCellWithReuseIdentifier: FeaturedCell.reuseIdentifier)
collectionView.register(MediumTableCell.self,
forCellWithReuseIdentifier: MediumTableCell.reuseIdentifier)
collectionView.register(SmallTableCell.self,
forCellWithReuseIdentifier: SmallTableCell.reuseIdentifier)
collectionView.register(ListTableCell.self,
forCellWithReuseIdentifier: ListTableCell.reuseIdentifier)
createDataSource()
reloadData()
}
public func configure<T: SelfConfiguringCell>(_ cellType: T.Type, with book: Book, for indexPath: IndexPath) -> T {
guard let cell = collectionView.dequeueReusableCell(
withReuseIdentifier: cellType.reuseIdentifier,
for: indexPath) as? T else {
fatalError("Unable to dequeue \(cellType)")
}
cell.configure(with: book)
return cell
}
public func createDataSource() {
dataSource = UICollectionViewDiffableDataSource<Section, Book>(collectionView: collectionView) { collectionView, indexPath, book in
switch self.sections[indexPath.section].type {
case "mediumTable":
return self.configure(MediumTableCell.self, with: book, for: indexPath)
case "smallTable":
return self.configure(SmallTableCell.self, with: book, for: indexPath)
case "listTable":
return self.configure(ListTableCell.self, with: book, for: indexPath)
default:
return self.configure(FeaturedCell.self, with: book, for: indexPath)
}
}
dataSource?.supplementaryViewProvider = { [weak self] collectionView, kind, indexPath in
guard let sectionHeader = collectionView.dequeueReusableSupplementaryView(
ofKind: kind,
withReuseIdentifier: SectionHeader.reuseIdentifier,
for: indexPath) as? SectionHeader else {
return nil
}
guard let firstBook = self?.dataSource?.itemIdentifier(
for: indexPath) else {
return nil
}
guard let section = self?.dataSource?.snapshot().sectionIdentifier(
containingItem: firstBook) else {
return nil
}
if section.title.isEmpty {
return nil
}
sectionHeader.title.text = section.title
sectionHeader.subtitle.text = section.subtitle
return sectionHeader
}
}
public func reloadData() {
var snapshot = NSDiffableDataSourceSnapshot<Section, Book>()
snapshot.appendSections(sections)
for section in sections {
snapshot.appendItems(section.items, toSection: section)
}
dataSource?.apply(snapshot)
}
public func createCompositionalLayout() -> UICollectionViewLayout {
let layout = UICollectionViewCompositionalLayout { sectionIndex, layoutEnvironment in
let section = self.sections[sectionIndex]
switch section.type {
case "mediumTable":
return self.createMediumTableSection(using: section)
case "smallTable":
return self.createSmallTableSection(using: section)
case "listTable":
return self.createListTableSection(using: section)
default:
return self.createFeaturedSection(using: section)
}
}
let config = UICollectionViewCompositionalLayoutConfiguration()
config.interSectionSpacing = 20
layout.configuration = config
return layout
}
public func createSectionHeader() -> NSCollectionLayoutBoundarySupplementaryItem {
let layoutSectionHeaderSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(0.93),
heightDimension: .estimated(80))
let layoutSectionHeader = NSCollectionLayoutBoundarySupplementaryItem(
layoutSize: layoutSectionHeaderSize,
elementKind: UICollectionView.elementKindSectionHeader,
alignment: .top)
return layoutSectionHeader
}
public func createFeaturedSection(using section: Section) -> NSCollectionLayoutSection {
let itemSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(1),
heightDimension: .fractionalHeight(1))
let layoutItem = NSCollectionLayoutItem(layoutSize: itemSize)
layoutItem.contentInsets = NSDirectionalEdgeInsets(
top: 0,
leading: 5,
bottom: 0,
trailing: 5)
let layoutGroupSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(0.93),
heightDimension: .estimated(288))
let layoutGroup = NSCollectionLayoutGroup.horizontal(
layoutSize: layoutGroupSize,
subitems: [layoutItem])
let layoutSection = NSCollectionLayoutSection(group: layoutGroup)
layoutSection.orthogonalScrollingBehavior = .groupPagingCentered
return layoutSection
}
public func createListTableSection(using section: Section) -> NSCollectionLayoutSection {
let itemSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(1/3),
heightDimension: .fractionalHeight(1))
let layoutItem = NSCollectionLayoutItem(layoutSize: itemSize)
layoutItem.contentInsets = NSDirectionalEdgeInsets(
top: 8,
leading: 8,
bottom: 8,
trailing: 8)
let layoutGroupSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(0.93),
heightDimension: .fractionalWidth(0.5))
let layoutGroup = NSCollectionLayoutGroup.horizontal(
layoutSize: layoutGroupSize,
subitems: [layoutItem])
let layoutSection = NSCollectionLayoutSection(group: layoutGroup)
layoutSection.orthogonalScrollingBehavior = .groupPagingCentered
return layoutSection
}
public func createMediumTableSection(using section: Section) -> NSCollectionLayoutSection {
let itemSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(1),
heightDimension: .fractionalHeight(0.33))
let layoutItem = NSCollectionLayoutItem(layoutSize: itemSize)
layoutItem.contentInsets = NSDirectionalEdgeInsets(
top: 0,
leading: 5,
bottom: 0,
trailing: 5)
let layoutGroupSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(0.93),
heightDimension: .fractionalWidth(0.55))
let layoutGroup = NSCollectionLayoutGroup.vertical(
layoutSize: layoutGroupSize,
subitems: [layoutItem])
let layoutSection = NSCollectionLayoutSection(
group: layoutGroup)
layoutSection.orthogonalScrollingBehavior = .groupPagingCentered
let layoutSectionHeader = createSectionHeader()
layoutSection.boundarySupplementaryItems = [layoutSectionHeader]
return layoutSection
}
public func createSmallTableSection(using section: Section) -> NSCollectionLayoutSection {
let itemSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(1),
heightDimension: .fractionalHeight(0.2))
let layoutItem = NSCollectionLayoutItem(layoutSize: itemSize)
layoutItem.contentInsets = NSDirectionalEdgeInsets(
top: 0,
leading: 20,
bottom: 0,
trailing: 0)
let layoutGroupSize = NSCollectionLayoutSize(
widthDimension: .fractionalWidth(0.93),
heightDimension: .estimated(200))
let layoutGroup = NSCollectionLayoutGroup.vertical(
layoutSize: layoutGroupSize,
subitems: [layoutItem])
let layoutSection = NSCollectionLayoutSection(
group: layoutGroup)
let layoutSectionHeader = createSectionHeader()
layoutSection.boundarySupplementaryItems = [layoutSectionHeader]
return layoutSection
}
}
听起来您想跳过某些部分，即使它们已配置和定义。我可以看到在你的实现中你正在这样做：
public func reloadData() {
var snapshot = NSDiffableDataSourceSnapshot<Section, Book>()
snapshot.appendSections(sections)
for section in sections {
snapshot.appendItems(section.items, toSection: section)
}
dataSource?.apply(snapshot)
}
将其更改为这样的内容：
public func reloadData() {
var snapshot = NSDiffableDataSourceSnapshot<Section, Book>()
var sectionsToInsert = sections.filter { eachSection in
//in order to skip sections (so that they are not visible in the collection view)
//simply do not append those sections to the data source
if someCriteria { //you determine what the criteria is
return true
}
}
snapshot.appendSections(sectionsToInsert)
for eachSection in sectionsToInsert {
//you can also hide sections by also not appending any items to that section
//if you do this, technically the section will still be there with 0 height
//however, if your section has any padding/margins, since the section is created earlier
//you will see the padding as specified in your layout
if anotherCriteria { //you determine what the criteria is
snapshot.appendItems(eachSection.items, toSection: eachSection)
}
}
dataSource?.apply(snapshot)
}