cellForItemAt is not calling in collectionView - ios

Question

I have a inputView where a collectionView will be displayed. I used auto layout for that inputView. When running the app numberOfItemsInSection is called but cellForItemAt is not called. So no cell is displaying. Did I do anything wrong using constraint?
I've also created project https://drive.google.com/file/d/0B5UHWsK1E6dSRDA5bmtSY2ZZbGs/view
ViewController.swift
override func viewDidLoad() {
super.viewDidLoad()
textField.inputView = InputPhotoView(frame: CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 265))
textField.becomeFirstResponder()
}
InputPhotoView.swift
class InputPhotoView: UIView {
let CellIdentifier = "Cell"
override init(frame: CGRect) {
super.init(frame: frame)
collectionView.dataSource = self
collectionView.register(CustomCell.self, forCellWithReuseIdentifier: CellIdentifier)
setupViews()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
fatalError("Not yet implented")
}
func setupViews() {
self.backgroundColor = UIColor.brown
self.addSubview(collectionView)
setupConstraints()
}
func setupConstraints() {
NSLayoutConstraint.activate([
collectionView.leadingAnchor.constraint(equalTo: self.trailingAnchor, constant: 50),
collectionView.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: 0),
collectionView.topAnchor.constraint(equalTo: self.topAnchor, constant: 0),
collectionView.bottomAnchor.constraint(equalTo: self.bottomAnchor, constant: 0)
])
}
public lazy var collectionView: UICollectionView = {
let layout = UICollectionViewFlowLayout()
layout.scrollDirection = .horizontal
layout.itemSize = CGSize(width: 100, height: 100)
layout.minimumInteritemSpacing = 0
layout.sectionInset = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
let collectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: layout)
collectionView.translatesAutoresizingMaskIntoConstraints = false
collectionView.contentInset = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
return collectionView
}()
}
DataSource
extension InputPhotoView : UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
print("number of items")
return 10
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: CellIdentifier, for: indexPath) as! CustomCell
return cell
}
}

Answer 1

Your code has constraint conflicts so the collectionView is not visible. Try changing this line:
collectionView.leadingAnchor.constraint(equalTo: self.trailingAnchor, constant: 50)
To something like this:
collectionView.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: 50)