Tag: ios

My first question on SO so bear with me. I have created a UICollectionViewController which has a header and 1 cell. Inside the cell is a tableview, inside the table view there are multiple static cells. One of those has a horizontal UICollectionView with cells which have UITextViews.

Problem: When tapping on a UITextView the collection view scrolls/jumps

Problem Illustration

On the right you can see the y offset values. On first tap it changes to 267 — the header hight. On a consecutive tap it goes down to 400 — the very bottom. This occurs no matter what I tried to do.

Note: Throughout my app I’am using IQKeyboardManager

What have I tried:

Disabling IQKeyboardManager completely and

1. Taping on text view
2. Replacing it with a custom keyboard management methods based on old SO answers

Set collectionView.shouldIgnoreScrollingAdjustment = true for:

1. all scrollable views in VC
2. Individuals scrollable views

Note: this property originates from the IQKeyboardManager Library and as far as I understand it is supposed to disable scroll adjustment offset.

Tried disabling scroll completely in viewDidLoad() as well as all other places within this VC. I used:

collectionView.isScrollEnabled = false
collectionView.alwaysBounceVertical = false  

Notably, I have tried disabling scroll in text viewDidBeginEditing as well as the custom keyboard management methods.

My Code:

The main UICollectionView and its one cell are created in the storyboard. Everything else is done programatically. Here is the flow layout function that dictates the size of the one and only cell:

extension CardBuilderCollectionViewController: UICollectionViewDelegateFlowLayout {
     func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: 
UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let height = view.frame.size.height
    let width = view.frame.size.width
    return CGSize(width: width * cellWidthScale, height: height * cellHeigthScale)
} 
}

Additionally, collectionView.contentInsetAdjustmentBehavior = .never

The TableView within the subclass of that one cell is created like so:

let tableView: UITableView = {
    let table = UITableView()
    table.estimatedRowHeight = 300
    table.rowHeight = UITableView.automaticDimension
    return table
}()

and:

    override func awakeFromNib() {
       super.awakeFromNib()     
        dataProvider = DataProvider(delegate: delegate)
        addSubview(tableView)
        tableView.fillSuperview() // Anchors to 4 corners of superview
        registerCells()
        tableView.delegate = dataProvider
        tableView.dataSource = dataProvider
    }

The cells inside the table view are all subclasses of class GeneralTableViewCell, which contains the following methods which determine the cells height:

var cellHeightScale: CGFloat = 0.2 {
    didSet {
        setContraints()
    }
}

private func setContraints() {
    let screen = UIScreen.main.bounds.height
    let heightConstraint = heightAnchor.constraint(equalToConstant: screen*cellHeightScale)
    heightConstraint.priority = UILayoutPriority(999)
    heightConstraint.isActive = true
}

The height of the nested cells (with TextView) residing in the table view is determined using the same method as the one and only cell in the main View.

Lastly the header is created using a custom FlowLayout:

class StretchyHeaderLayout: UICollectionViewFlowLayout {
    
    override func layoutAttributesForElements(in rect: CGRect) -> (UICollectionViewLayoutAttributes)? {
        let layoutAttributes = super.layoutAttributesForElements(in: rect)
        
        layoutAttributes?.forEach({ (attribute) in
            if attribute.representedElementKind == UICollectionView.elementKindSectionHeader  && attribute.indexPath.section == 0 {
                
                guard let collectionView = collectionView else { return }
                
                attribute.zIndex = -1
                let width = collectionView.frame.width
                let contentOffsetY = collectionView.contentOffset.y
                print(contentOffsetY)
                if contentOffsetY > 0 { return }
                let height = attribute.frame.height - contentOffsetY
                attribute.frame = CGRect(x: 0, y: contentOffsetY, width: width, height: height)
            }
        })
        return layoutAttributes
    }
    
    override func shouldInvalidateLayout(forBoundsChange newBounds: CGRect) -> Bool {
        return true
    }
}

This is my first time designing a complex layout with mostly a programatic approach. Hence it is possible that I missed something obvious. However, despite browsing numerous old questions I was not able to find a solution. Any solutions or guidance is appreciated.