How to make scrollview scroll separately to its content height in swift - swift

Question

I have view hierarchy like below in storyboard
here for content main constrains top = 0, leading = 0, trailing = 0, bottom = 0
here for scrollview constrains top = 0, leading = 0, trailing = 0, bottom = 0
here for View constrains top = 0, leading = 0, trailing = 0, bottom = 0
for ContentView constrains top = 0, leading = 0, trailing = 0
for TblReview constrains top = 0, leading = 0, trailing = 0, bottom = 20
for Productcollectionview constrains top = 0, leading = 0, trailing = 0, bottom = 20, height = 400
and i have Productcollectionview height outlet like below in swift file
and i don't want collectionview separate scrolling.. i want total view to scroll according to collectionview cells.. so for that i have written below code but with this code contentView and tblReview also scrolling upto productioncollectionview height i need contentView should scroll upto its content height and tblReview should scroll upto its rows
how to make scrolling separately to its height.
please help me to solve this issue
#IBOutlet weak var productCollHeight: NSLayoutConstraint!
override func viewDidLoad() {
super.viewDidLoad()
productCollectionView.addObserver(self, forKeyPath: "contentSize", options: .new, context: nil)
}
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
let collectionView = object as? UICollectionView
if collectionView == self.productCollectionView{
if(keyPath == "contentSize"){
if let newvalue = change?[.newKey]
{
let newsize = newvalue as! CGSize
self.productCollHeight.constant = newsize.height
}
}
}
}
#IBAction func aboutCompany(_ sender: UIButton){
self.productCollectionView.isHidden = true
self.tblReview.isHidden = true
self.contentView.isHidden = false
}
#IBAction func review(_ sender: UIButton){
self.productCollectionView.isHidden = true
self.tblReview.isHidden = false
self.contentView.isHidden = true
}
#IBAction func productOfSeller(_ sender: UIButton){
self.productCollectionView.isHidden = false
self.tblReview.isHidden = true
self.contentView.isHidden = true
}
and i am hiding and showing tblReview and contentView according to need
with the above code tblReview and contentView are also scrolling upto productCollectionView height.. please help me to solve this error
EDIT: share this seller is out of scrollview so here contentView height is not not so long but if i scroll the contentView also scrolling too long like productioncollectionview
this is contentView which is scrolling too long like productioncollectionview

Answer 1

if your all constraint are proper than just use it like this you don't need to count every time. UICollectionView has intrinsicContentSize it will count it properly.
final class ContentSizedCollectionView: UICollectionView {
override var contentSize:CGSize {
didSet {
invalidateIntrinsicContentSize()
}
}
override var intrinsicContentSize: CGSize {
layoutIfNeeded()
return CGSize(width: UIView.noIntrinsicMetric, height: contentSize.height)
}
}
put that code in controller or wherever you wan to put and assign ContentSizedCollectionView class to your collectionview.
NOTE: you can also use it with UITableView after creating for UITableView.