ScrollView partially hidden by navigation bar (large titles)

[Mattesackboy]

When we force refresh using the HeadRefresh (with NormalHeaderAnimator), when the scrollView populates with cells (in my case is a collectionView) the first cell is partially hidden behind the navigation bar, but after touching/scrolling the scrollView the collectionView automatically snaps itself on the correct position and the bug is gone.

After headRefresh finishes to load the data:

After touching/scrolling the collectionView:

Has anyone experienced this before? How can I fix it?

[BarredEwe]

Hey! You can mention a user like this: @Mattesackboy.
If you create an example project in which I can reproduce the error, I will try to help you.

[Mattesackboy]

@BarredEwe I've tried to mention you, but without success because you were not on the discussion thread/a collaborator to the project. By the way thanks for your time ❣️
Right now I'm at work, but as soon as possible I'll try to reproduce this on a Test project and send it to you!
Thanks again 🙏🏻

[Mattesackboy]

Hey @BarredEwe, I've tried to simulate this problem on a Test environment (because I'm sorry but I can't share the whole project where this bug is present) but unsuccessfully.
I could, by the way, find the cause of this bug.
The ViewController where this happens uses a UICollectionView as root-view (UICollectionViewController) with a Flow layout.
On the initializer we have this code:

init(layout: UICollectionViewLayout = UICollectionViewFlowLayout()) {
     super.init(collectionViewLayout: layout)
     if let layout = layout as? UICollectionViewFlowLayout {
          layout.scrollDirection = .vertical
          layout.sectionInset = .init(top: 16, left: 16, bottom: 16, right: 16)
          layout.minimumInteritemSpacing = 0
          layout.minimumLineSpacing = 16
          layout.itemSize = .init(width: collectionView.frame.width - 16*2, height: 180)
     }
 }

By removing the layout.sectionInset = .init(top: 16, left: 16, bottom: 16, right: 16) line, the bug is gone.
Here are 2 videos that demonstrate the problem with the relative fix:

With section inset active (set to: .init(top: 16, left: 16, bottom: 16, right: 16)):

IMG_1753.MP4

Without section inset active:

IMG_1754.MP4

[Mattesackboy]

I've also tried it on the simulator, and this bug doesn't happen on it. It happens only on real devices (such as my iPhone X) and only on iOS 14+ (this was not present last year on iOS 13, and we didn't update the app since then).

[Mattesackboy]

I may have found a fix to this. Instead of setting the layout.sectionInset (UICollectionViewFlowLayout) top and bottom insets, I need to set the collectionView.contentInset instead.
In my case, this can be done easily because I don't have multiple sections on the collectionView, but if someone would have multiple sections could experience the same bug.