Pure code builds the collection but UICollectionViewDelegateFlowLayout is not executed - ios

Question

Pure code (I didn't use the storyboard, just use code) builds the collection but UICollectionViewDelegateFlowLayout is not executed.
class Calendarview : UIView , UICollectionViewDelegate , UICollectionViewDataSource , UICollectionViewDelegateFlowLayout {
var collectionview : UICollectionView!
override func didAddSubview(_ subview: UIView) {
}
override func didMoveToSuperview() {
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
collectionview = UICollectionView(frame: CGRect(x: 0, y: 0, width: self.bounds.width, height: self.bounds.height) , collectionViewLayout: layout)
collectionview.frame = self.frame
collectionview.register(CalendarCell.self, forCellWithReuseIdentifier: "Cell")
collectionview.dataSource = self
collectionview.delegate = self
self.addSubview(collectionview!)
collectionview.reloadData()
}
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
return 42
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, referenceSizeForFooterInSection section: Int) -> CGSize {
return CGSize(width: self.bounds.width / 7, height: self.bounds.height / 3)
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
return 5
}
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
return 5
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath) as! CalendarCell
cell.lbshow = UILabel(frame: cell.bounds)
cell.lbshow.text = String(indexPath.row)
cell.addSubview(cell.lbshow)
cell.backgroundColor = .blue
return cell
}
}

Answer 1

Set delegate as self.collectionView.delegate = self;. UICollectionViewDelegateFlowLayout inherits from UICollectionViewDelegate. So it will called all methods of UICollectionViewDelegateFlowLayout.
Hence, You need to set self.collectionView.collectionViewLayout to your flow layout.
let layout: UICollectionViewFlowLayout = UICollectionViewFlowLayout()
layout.estimatedItemSize = CGSize(width: 10, height: 10)
layout.itemSize = CGSize(width: 200, height: 200)
layout.minimumLineSpacing = 10
layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
layout.scrollDirection = .horizontal
collectionview.collectionViewLayout = layout