hidesbarsonswipe mutates view size - ios

Question

I am having trouble with this piece of code:
navigationController?.hidesBarsOnSwipe = true
My navigation controller's root view controller is a UICollectionViewController. The blue view below is a cell that represents the user's current screen. I think the problem is that I need to resize the cell when the navigation bar hides.
I set the cell size like this:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: view.frame.width, height: view.frame.height - 44)
}
I am not breaking any constraints, and I am very sure everything is set up properly. But when I swipe up, this happens:
Before
After
As you can see, the view gets shortened. I can't find those measurements anywhere in my code.
Is there a way to ensure that the view gets resized properly?

Answer 1

Put this in your viewDidLoad() and you should be good to go.
self.edgesForExtendedLayout = []
yourBlueView.translatesAutoresizingMaskIntoConstraints = false
view.addSubview(yourBlueView)
yourBlueView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
yourBlueView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
yourBlueView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
yourBlueView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
Edit:
Change yourBlueView to the name you've given that particular UIView. Let me know if you get stuck, but do try to figure it out first. That's the best way to learn it and retain it.
The bar on the bottom takes at least 44 and I notice it's going under the nav bar at the top. Remove your hard code sizing which is too high, and only use the auto layout
Second Edit: (This is a non-autolayout approach)
let reuseIdentifier = "Cell"
This code goes in viewDidLoad:
// Do any additional setup after loading the view, typically from a nib.
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
layout.sectionInset = UIEdgeInsets(top: 20, left: 10, bottom: 10, right: 10)
let displaySize = UIScreen.main.bounds
let displayHeight = displaySize.height - 40
let displayWidth = displaySize.width
layout.itemSize = CGSize(width: displayWidth, height: displayHeight)
if let collectionView = UICollectionView(frame: self.view.bounds, collectionViewLayout: layout) {
collectionView.dataSource = self
collectionView.delegate = self
collectionView.register(UICollectionViewCell.self, forCellWithReuseIdentifier: reuseIdentifier)
collectionView.backgroundColor = UIColor.white
self.view.addSubview(collectionView!)
}