Dynamic height noScrolable UICollectionView in UICollectionViewCell - ios

Question

I want to add a dynamic height nonScrollable UICollectionView into UICollectionViewCell. (It is easy to add a static height UICollectionView in UICollectionViewCell as explained by Ash Furrow)
After spending hours on searching through the web I still don't get it.
This is what I want
Lets call:
Main CollectionView: ParentCollectionView
Inside CollectionView: ChildCollectionView
I want to get the height of ChildCollectionView so that i can set the cell size of the ParentCollectionView in side:
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let text = "I'm trying to get a label in a cell.."
let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
let estimatedFrameForEventText = (text as NSString).boundingRect(with: CGSize.init(width: view.frame.width - 30, height: 1000), options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 12)], context: nil)
return CGSize.init(width: view.frame.width - 10, height: 320 + estimatedFrameForEventText.height + 60)
}
Also want to change the height constant of the ChildCollectionView with this:
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: eventCellId, for: indexPath) as! EventCell
cell.eventText.text = "I'm trying to get a label in a cell.."
// height constraint of ChildCollectionView in ParentCell
cell.collectionViewHeightConstraint.constant = cell.collectionView.intrinsicContentSize.height
return cell
}
The scrolling of ChildCollectionView is purposely disabled to show the ChildCollectionViewCells all together.
This is where I am stuck
I am not abel to preCalculate the ChildCollectionView to pass them in the ParentCollectionView delegates
Both the CollectionView uses UICollectionViewFlowLayout
I am new to iOS developing.
Any help would be appreciated :)

Answer 1

This solves my problem
ParentCollectionViewController
var height: CGFloat!
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: eventCellId, for: indexPath) as! EventCell
cell.collectionViewHeightConstraint.constant = height!
return cell
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
let options = NSStringDrawingOptions.usesFontLeading.union(.usesLineFragmentOrigin)
var sizeOfChildCell: CGRect!
var widthOfCells: CGFloat! = 0.0
let cellPadding = 10
let widthOfChildCollectionview = view.frame.width - 120
for tag in tags {
sizeOfChildCell = ("#\(tag)" as NSString).boundingRect(with: CGSize.init(width: widthOfChildCollectionview, height: 1000), options: options, attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 12)], context: nil)
widthOfCells = widthOfCells + sizeOfChildCell.width + cellPadding + 3.8
}
let numOfRows = ceil(widthOfCells / widthOfChildCollectionview)
height = numOfRows * 25
height = height + numOfRows * 3.8
return CGSize.init(width: view.frame.width - 10, height: 320 + height)
}
ParentCollectionViewCell
var childCollectionViewHeightConstraint: NSLayoutConstraint!
lazy var childCollectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
let cv = UICollectionView(frame: .zero, collectionViewLayout: layout)
cv.showsVerticalScrollIndicator = false
cv.isScrollEnabled = false
cv.contentInset = UIEdgeInsetsMake(0, 0, 0, 0)
cv.backgroundColor = .white
cv.dataSource = self
cv.delegate = self
return cv
}()
override init(frame: CGRect) {
super.init(frame: frame)
childCollectionViewHeightConstraint = NSLayoutConstraint(item: childCollectionView, attribute: .height, relatedBy: .equal, toItem: nil, attribute: .notAnAttribute, multiplier: 1.0, constant: 96)
addConstraint(childCollectionViewHeightConstraint)
}

Answer 2

Just for future searches on this subject. I'm using IGListKit with a cell that contains a UICollectionView that holds my tags. My problem was that IGListKit isn't built very well on the AutoLayout principles so to prevent the collectionview cells from overlapping each other I had to calculate the height for the section manually before it's shown.
My idea was to just add the width of each tag (+ padding + minimumInterimSpace) and determine when the next tag supersedes the collection view width.
func calculateDimensions() {
//This is how IGListKit forwards the width, could be replaced with collectionView.containerSize.width
let width = collectionContext!.containerSize.width
var lineWidth:CGFloat = 0.0
var lines = 0
for tag in data.arrTags {
//Calculate bounds by using boundingRect
let size = TextSize.size(tag, font: Font.fontRegular(size: 13), height: 30)
//16= 8 padding-left + 8 padding-right
//5 = minimumInterimSpace
let itemWidth = 16 + size.width + 5
let tmpWidth = lineWidth + itemWidth
if tmpWidth > width {
lines += 1
lineWidth = itemWidth
}
lineWidth += itemWidth
}
sectionHeight = CGFloat( lines * 30 + (lines * 5)) + 15
}
This method is called when IGListKit sets the size for the current section. So I did this:
override func sizeForItem(at index: Int) -> CGSize {
calculateDimensions()
let size = CGSize(width: collectionContext!.containerSize.width, height: sectionHeight)
return size
}
This will result in the following: