Ios collectionview全局标头不会向下推单元格,而是保持在顶部
我有一个集合视图标题(蓝色)和单元格(红色)。我希望能够以编程方式显示/隐藏标题,但是当我以编程方式显示标题时,它会显示在单元格顶部(或使scrollview稍微向下)。我希望标题向下推整个scrollview,这样我就不必在单击“切换标题”后向上滚动 我非常努力地为下面的问题重现最少的代码。请分享任何见解Ios collectionview全局标头不会向下推单元格,而是保持在顶部,ios,swift,uicollectionview,uikit,uicollectionviewcompositionallayout,Ios,Swift,Uicollectionview,Uikit,Uicollectionviewcompositionallayout,我有一个集合视图标题(蓝色)和单元格(红色)。我希望能够以编程方式显示/隐藏标题,但是当我以编程方式显示标题时,它会显示在单元格顶部(或使scrollview稍微向下)。我希望标题向下推整个scrollview,这样我就不必在单击“切换标题”后向上滚动 我非常努力地为下面的问题重现最少的代码。请分享任何见解 struct Section: Hashable { var items: [Int] } class ViewController: UIViewController {
struct Section: Hashable {
var items: [Int]
}
class ViewController: UIViewController {
var collectionView: UICollectionView!
var dataSource: UICollectionViewDiffableDataSource<Section, Int>?
var showHeader = true
override func viewDidLoad() {
super.viewDidLoad()
collectionView = UICollectionView(frame: view.frame, collectionViewLayout: createCompositionalLayout())
collectionView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
collectionView.backgroundColor = .systemBackground
collectionView.register(CellView.self, forCellWithReuseIdentifier: "cellId")
collectionView.register(HeaderView.self, forSupplementaryViewOfKind: UICollectionView.elementKindSectionHeader, withReuseIdentifier: "headerId")
view.addSubview(collectionView)
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor).isActive = true
collectionView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor).isActive = true
collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
createDataSource()
addData()
}
func createCompositionalLayout() -> UICollectionViewLayout {
// layout for cell
let layout = UICollectionViewCompositionalLayout { sectionIndex, layoutEnvironment in
let itemSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .fractionalHeight(1))
let layoutItem = NSCollectionLayoutItem(layoutSize: itemSize)
layoutItem.contentInsets = NSDirectionalEdgeInsets(top: 10, leading: 0, bottom: 10, trailing: 0)
let layoutGroupSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .absolute(200))
let layoutGroup = NSCollectionLayoutGroup.vertical(layoutSize: layoutGroupSize, subitems: [layoutItem])
let layoutSection = NSCollectionLayoutSection(group: layoutGroup)
return layoutSection
}
let config = UICollectionViewCompositionalLayoutConfiguration()
if showHeader {
let layoutSectionHeader = createGlobalHeader()
config.boundarySupplementaryItems = [layoutSectionHeader]
}
layout.configuration = config
return layout
}
func createGlobalHeader() -> NSCollectionLayoutBoundarySupplementaryItem {
let layoutSectionHeaderSize = NSCollectionLayoutSize(widthDimension: .fractionalWidth(1), heightDimension: .absolute(50))
let layoutSectionHeader = NSCollectionLayoutBoundarySupplementaryItem(layoutSize: layoutSectionHeaderSize, elementKind: UICollectionView.elementKindSectionHeader, alignment: .top)
layoutSectionHeader.pinToVisibleBounds = true
return layoutSectionHeader
}
func createDataSource() {
dataSource = UICollectionViewDiffableDataSource<Section, Int>(collectionView: collectionView) { collectionView, indexPath, item in
guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cellId", for: indexPath) as? CellView else { fatalError("Unable to dequeue ") }
cell.button.addTarget(self, action: #selector(self.onButtonClick), for: .touchUpInside)
return cell
}
dataSource?.supplementaryViewProvider = { (collectionView, kind, indexPath) in
guard let header = collectionView.dequeueReusableSupplementaryView(ofKind: kind, withReuseIdentifier: "headerId", for: indexPath) as? HeaderView else { return nil }
return header
}
}
@objc func onButtonClick() {
print("toggle")
showHeader.toggle()
collectionView.collectionViewLayout = createCompositionalLayout()
collectionView.layoutIfNeeded()
}
func addData() {
var snapshot = NSDiffableDataSourceSnapshot<Section, Int>()
var sections: [Section] = []
sections.append(Section(items: [0,1,2,3,4,5,6,7,8,9,10,11,12]))
snapshot.appendSections(sections)
for section in sections {
snapshot.appendItems(section.items, toSection: section)
}
dataSource?.apply(snapshot)
}
}
class CellView: UICollectionViewCell {
let button = UIButton()
override init(frame: CGRect) {
super.init(frame: frame)
backgroundColor = .red
addSubview(button)
button.setTitle("Toggle header", for: .normal)
button.setTitleColor(.black, for: .normal)
button.translatesAutoresizingMaskIntoConstraints = false
button.topAnchor.constraint(equalTo: topAnchor).isActive = true
button.leadingAnchor.constraint(equalTo: leadingAnchor).isActive = true
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class HeaderView: UICollectionReusableView {
override init(frame: CGRect) {
super.init(frame: frame)
backgroundColor = .blue
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
struct节:可散列{
变量项:[Int]
}
类ViewController:UIViewController{
var collectionView:UICollectionView!
var数据源:UICollectionViewDiffableDataSource?
var showHeader=true
重写func viewDidLoad(){
super.viewDidLoad()
collectionView=UICollectionView(frame:view.frame,collectionViewLayout:createCompositionalLayout())
collectionView.autoresizingMask=[.flexibleWidth、.flexibleHeight]
collectionView.backgroundColor=.systemBackground
collectionView.register(CellView.self,强制使用ReuseIdentifier:“cellId”)
collectionView.register(HeaderView.self,用于种类的SupplementViewofKind:UICollectionView.elementKindSectionHeader,带有ReuseIdentifier:“headerId”)
view.addSubview(collectionView)
collectionView.TranslatesAutoResizezingMaskintoConstraints=false
collectionView.topAnchor.constraint(equalTo:view.SafeArealLayoutGuide.topAnchor)。isActive=true
collectionView.bottomAnchor.constraint(equalTo:view.SafeArealLayoutGuide.bottomAnchor).isActive=true
collectionView.leadingAnchor.constraint(等式:view.leadingAnchor).isActive=true
collectionView.trailingAnchor.constraint(equalTo:view.trailingAnchor).isActive=true
createDataSource()
addData()
}
func createCompositionalLayout()->UICollectionViewLayout{
//单元布局
让layout=UICollectionViewCompositionLayout{sectionIndex,layoutEnvironment在
让itemSize=NSCollectionLayoutSize(宽度维度:。分数宽度(1),高度维度:。分数高度(1))
let layoutItem=NSCollectionLayoutItem(layoutSize:itemSize)
layoutItem.contentInsets=NSDirectionalEdgeInsets(顶部:10,前导:0,底部:10,尾随:0)
let layoutGroupSize=NSCollectionLayoutSize(宽度维度:。分数宽度(1),高度维度:。绝对(200))
let layoutGroup=NSCollectionLayoutGroup.vertical(layoutSize:layoutGroupSize,子项:[layoutItem])
let layoutSection=NSCollectionLayoutSection(组:layoutGroup)
返回布局部分
}
let config=UICollectionViewCompositionalLayoutConfiguration()
如果显示标题{
让layoutSectionHeader=createGlobalHeader()
config.boundarySupplementaryItems=[layoutSectionHeader]
}
layout.configuration=config
返回布局
}
func createGlobalHeader()->nsCollectionLayoutBoundary补充项{
让layoutSectionHeaderSize=NSCollectionLayoutSize(宽度维度:。分数宽度(1),高度维度:。绝对(50))
let layoutSectionHeader=nsCollectionLayoutBoundary补充项(layoutSize:layoutSectionHeaderSize,elementKind:UICollectionView.elementKindSectionHeader,对齐:.top)
layoutSectionHeader.pinToVisibleBounds=true
返回布局部分标题
}
func createDataSource(){
dataSource=UICollectionViewDiffableDataSource(collectionView:collectionView){collectionView,indexPath,中的项
guard let cell=collectionView.dequeueReusableCell(带有ReuseIdentifier:“cellId”,for:indexPath)作为?CellView else{fatalError(“无法出列”)}
cell.button.addTarget(self,action:#选择器(self.onButtonClick),for:.touchUpInside)
返回单元
}
dataSource?.supplementaryViewProvider={(collectionView,kind,indexPath)中的
guard let header=collectionView.dequeueReusableSupplementaryView(ofKind:kind,带有ReuseIdentifier:“headerId”,for:indexPath)作为?HeaderView else{return nil}
回流集管
}
}
@objc func onButtonClick(){
打印(“切换”)
showHeader.toggle()
collectionView.collectionViewLayout=createCompositionalLayout()
collectionView.layoutIfNeeded()的
}
func addData(){
var snapshot=NSDiffableDataSourceSnapshot()
变量节:[节]=[]
章节。附加(章节(项目:[0,1,2,3,4,5,6,7,8,9,10,11,12]))
快照.附加节(节)
一节接一节{
snapshot.appendItems(section.items,toSection:section)
}
数据源?.apply(快照)
}
}
类CellView:UICollectionViewCell{
let button=UIButton()
重写初始化(帧:CGRect){
super.init(frame:frame)
背景颜色=.red
添加子视图(按钮)
button.setTitle(“切换标题”,用于:。正常)
button.setTitleColor(.black,表示:。正常)
button.translatesAutoresizingMaskIntoConstraints=false
button.topAnchor.constraint(equalTo:topAnchor).isActive=true
button.leadingAnchor.constraint(等于:leadingAnchor).isActive=true
}
必需初始化?(编码器:NSCoder){
fatalError(“初始化(编码者:)尚未实现”)
}
}
类HeaderView:UICollectionReusableView{
重写初始化(帧:CGRect){
super.init(frame:frame)
背景颜色=.blue
}
必需初始化?(编码器:NSCoder){
fatalError(“初始化(编码者:)尚未实现”)
}
}
我认为您需要嵌入该集合
collectionView.setContentOffset(.zero, animated: false)