Ios 如何创建跨越多个节的粘性标题

我有一个集合视图，其中每个单元格都是一个部分。我需要实现一个“粘性头”，它将跨越3个部分，直到另一个“粘性头”取代它。我该怎么做？由于其他原因，我无法将我的单元格更改为全部共享同一分区。

我将仅在第一个分区演示如何执行此操作。因为使用了一些常量，所以它是相当不成熟的。然而，如果你遵循这个模式，你可以更容易地实现你的目标

为了达到高精度，请随意更改代码

基本上，只需将UICollectionViewFlowLayout子类化

class MyCollectionViewFlowLayout: UICollectionViewFlowLayout{

lazy var offset : CGFloat? = { return self.collectionView?.contentOffset.y}()

// only first section here, you need to add other sections programmatically later.
override func invalidationContext(forBoundsChange newBounds: CGRect) -> UICollectionViewLayoutInvalidationContext{
   let result =   super.invalidationContext(forBoundsChange: newBounds)
   result.invalidateSupplementaryElements(ofKind: UICollectionView.elementKindSectionHeader, at: [IndexPath.init(row: 0, section: 0)])
    return result
}


  override func layoutAttributesForSupplementaryView(ofKind elementKind: String, at indexPath: IndexPath) -> UICollectionViewLayoutAttributes?{
  let result =  super.layoutAttributesForSupplementaryView(ofKind: elementKind, at: indexPath)
    guard indexPath.section % 3 == 0 else {
        return result
    }
    let section = CGFloat (indexPath.section / 3)

    let   totalHeight : CGFloat =  414.0 +  1390.0 * (section)  //414 = first section height
    // 1390 = height of three sections
    let   totalNextHight : CGFloat = 1390.0 * (section + 1)

    if let result = result {
    if result.frame.origin.y >  CGFloat(totalHeight) {
          result.frame = CGRect.init(x: result.frame.origin.x , y:  (result.frame.origin.y < totalNextHight) ? (self.collectionView?.contentOffset.y)! - offset! + totalHeight : totalNextHight, width: result.frame.width, height: result.frame.height)

        }
    }
    return result
}

}

这些代码背后有很多工作要做。希望你能尽快找到自己的答案

extension MyCollectionViewController: UICollectionViewDelegateFlowLayout {

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForHeaderInSection section: Int) -> CGSize{
    if section % 3 == 0  {return CGSize.init(width:200 , height: 44)}
    return CGSize.init(width:0 , height: 0)
   }