UICollectionView sticky header (sectionHeadersPinToVisibleBounds) disappears for while after inserting section when collection is overscrolled (bounce effect)

Number:rdar://48363057 Date Originated:February 25 2019
Status:Open Resolved:
Product:iOS + SDK Product Version:iOS 11.x and 12.x
Classification: Reproducible:Always

`UICollectionView` with 
    - `UICollectionViewCell` cells
    - `UICollectionReusableView` section headers
    - `UICollectionViewFlowLayout` collections's layout
    - `sectionHeadersPinToVisibleBounds ` is enabled

If the insertion (`insertItemsAtIndexPaths` inside `performBatchUpdates` block) happens when collection is overscrolled (bounce is enabled), header will disappear for while. See attached video.

Steps to Reproduce:
Start the attached example project and scroll to the bottom quickly and keep collection overscrolled (keep it bouncing - as you can see in the attached video).

Expected Results:
Header will be unchanged after section insertion (sticky). See attached "Expected look" image.

Actual Results:
Header disappears when insertion becomes during collection overscroll at the bottom (bounce effect). See attached "Look after section insertion with overscrolled collection" image.

iPhone 7 with iOS 12.1.4 or any simulator with iOS 11.x and 12.x

iPhone 7 with iOS 12.1.4 or any simulator with iOS 11.x and 12.x


Example project, video and images showing described issue:

By jm.jakubmarek at Feb. 26, 2019, 9:37 a.m. (reply...)

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