Creating UIcollectionView with Waterfall layout and self sizing cell - swift3

Question

I am trying to implement waterfallLayout with a self sizing cell that should work with iOS >= 9.0
Something like pintrest collectionViewLayout not the transition but the difference is that i have a fixed ratio of image but fields below is dynamic which i used UIStackView.
The self sizing is working fine but my problem is in changing the cell origin to be always = 15 PX between cells.
so when i tried FlowLayout without any customisation everything is working fine except for the margins between cells is not correct but the scrolling is working well without any performance issue for iOS >= 9.0
After trying CustomizingFlowLayout the performance is so bad in iOS 10 things is not working while in iOS 9 works fine. i know that apple did some improvement with the UICollectionView but with me i don't see that improvement.
My Cell:
override func preferredLayoutAttributesFitting(_ layoutAttributes: UICollectionViewLayoutAttributes) -> UICollectionViewLayoutAttributes {
self.setNeedsLayout()
self.layoutIfNeeded()
layoutAttributes.bounds.size.height = systemLayoutSizeFitting(layoutAttributes.size, withHorizontalFittingPriority: UILayoutPriorityRequired, verticalFittingPriority: UILayoutPriorityFittingSizeLevel).height
return layoutAttributes
}
My controller:
ViewDidLoad {
layoutView = collectionView.collectionViewLayout as! CustomLayout
if #available(iOS 10.0, *) {
self.collectionView.isPrefetchingEnabled = false
}
layoutView.estimatedItemSize = CGSize(width: layoutView.cellWidth, height: 200)
}
extension RecipesCollectionWithSortBar: UICollectionViewDataSource {
func numberOfSections(in collectionView: UICollectionView) -> Int {
return 1
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return array.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: customCell.reuseIdentifier, for: indexPath) as! customCell
return cell
}
extension RecipesCollectionWithSortBar : UICollectionViewDelegateFlowLayout {
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if scrollView.bounds.maxY == scrollView.contentSize.height && !isLoadingMoreRecipes {
//
LoadMore
}
}
My CustomFlowLayout
override func layoutAttributesForElements(in rect: CGRect) -> [UICollectionViewLayoutAttributes]? {
let attrs = super.layoutAttributesForElements(in: rect)
var attrsCopy = [UICollectionViewLayoutAttributes]()
for element in attrs! where (element.copy() as! UICollectionViewLayoutAttributes).representedElementCategory == .cell
&& element.frame.height != cacheCells[element.indexPath.item]?.frame.height {
if element.indexPath.item == 0 {
element.frame.origin.y = self.sectionInset.top
element.frame.origin.x = self.sectionInset.left
} else if element.indexPath.item == 1 {
element.frame.origin.y = self.sectionInset.top
element.frame.origin.x = cacheCells[0]!.frame.maxX + margin
} else {
let previous = cacheCells[element.indexPath.item - 2]
element.frame.origin.y = previous!.frame.maxY + self.minimumInteritemSpacing
element.frame.origin.x = previous!.frame.origin.x
}
cacheCells[element.indexPath.item] = element
attrsCopy.append(element)
}
let values = cacheCells.values.filter({ $0.frame.intersects(rect) })
return values.map({ $0 })
}
Here i have many problems :
1- i have a huge white space at the end of the collectionView because i changed the cell origin this problem only happens at iOS > 10.
i tried to override the content size
func getContentHeight() -> CGFloat {
if !cacheCells.values.isEmpty {
let attribute = cacheCells.values.max { $0.0.frame.maxY < $0.1.frame.maxY }
return attribute!.frame.maxY + sectionInset.bottom
}
return contHeight
}
override var collectionViewContentSize: CGSize {
return CGSize(width: self.cellWidth * CGFloat(columnCount), height: getContentHeight())
}
for some reason iOS 9 don't like this solution the scroll stops ..
2- Scrolling performance is so bad in iOS 10 and worst in iOS 9.0.
3- when i load more believe it or not it scroll 3 or 4 times and doesn't have more items to show when i print the log (i have 100 item but the collection view show only 70) and sometimes when hard scrolling it remembers that there's some more items and show them. i am not sure what i am doing wrong.
It's been 2 weeks now trying to figure out what's wrong may be having some fresh eye and mind can point on the problem i am having.