UICollectionViewLayout for Google Chrome tab (iOS app).

My project needs a user interface like Google Chrome Tab Switcher. There was a question like this in the past, but the answers are mostly out of date as it was written 5 years ago, and the answers were about Evernote's static and overlapping UI ( here ). I tried for a few days, but the best I could get was something really sluggish. Also interesting, when coded it worked in some areas, then it doesn't. I didn't pick any code because, to be honest, my code is probably more wrong than correct and I have to start from the beginning.

What makes it so confusing? The bottom bottom should be initially 100% visible, then 50%, 25% (relative to their height), and also obviously scrollable. Scrolling direction like chrome, first (last) at the bottom and last at the top. However, I would also like the distance between the first and second to increase, if you scroll down to see less fresh views, the second should be 100% visible as the bottom app disappears from the screen.

Yes, this is a jailbreak project, but this is inappropriate as I have coded a replica in the iOS simulator for this part. It's just a layout issue for the UICollectionView. The rest of the project was coded