snapping issue while switching bewteen UICollectionViews

[Xuan]

I have two tabs, each tab contains a UICollectionView, and a BLKHeightBar as the shared title view.
snap is enabled and set to 0.5 threshold.

tab 1 contains 6 cells and tab 2 containts 20 cells, so normally, tab 1 will always bounce back to progress 0, while tab 2 can snap to 1 and 0.

When I switch to tab 2, scroll tab 2 and make it snap to progress 1, and then I switch to tab 1, while the height bar stays at progress 1,

Then when I switch again back to tab 2, now I cannot snap tab 2 back to progress 0. When I see the self.flexibleHeightBar.progress is set to 0, after that it is snapping back to progress 1, which is wrong. I feel it should not snap to progress 1 while self.flexibleHeightBar.progress == 1.

It seems like some variable is not updating the current scroll view properties?
How could I continue debug it and fix it?

[Xuan]

when I tried to set each tab scroll view(UICollectionView to be correct), and I found that I maybe did it incorrectly:
targetCollectionView.contentInset = UIEdgeInsetsMake(self.navigationBar.frame.size.height, 0, 20, 0);

The idea is I want to keep the scroll view contentInset consistent, so when the height bar is at minimum height, I still get the correct Inset.

I am trying to use contentOffset to adjust the offset, instead of changing contentInset.

The contentInset I think should always be
targetCollectionView.contentInset = UIEdgeInsetsMake(self.navigationBar.maximumBarHeight, 0, 20, 0);