Data Source for CollectionView inside CollectionViewCell is always nil - ios

Question

I have a UICollectionView inside a UICollectionViewCell, and a separate NSObject that is the dataSource. I am able to set the dataSource for the external UICollectionView, but not the internal one.
Here's the cell containing the internal UICollectionView:
class FeaturedCell: UICollectionViewCell, UICollectionViewDelegate {
#IBOutlet var collectionView: UICollectionView!
let data = FeaturedData()
override init(frame: CGRect) {
super.init(frame: frame)
//setUp()
}
required init?(coder: NSCoder) {
super.init(coder: coder)
}
func setUp() {
collectionView.dataSource = data
collectionView.delegate = self
collectionView.reloadData()
}
}
extension FeaturedCell {
func setCollectionViewDataSourceDelegate <D: FeaturedData> (_ dataSourceDelegate: D, forRow row: Int) {
collectionView.delegate = dataSourceDelegate
collectionView.dataSource = dataSourceDelegate
collectionView.reloadData()
print("Reload Data")
}
}
And the UIView containing the external UICollectionView:
class MainView: UIView, UICollectionViewDelegate {
#IBOutlet var collectionView: UICollectionView!
let data = MainData()
override func awakeFromNib() {
setUp()
}
func setUp() {
collectionView.dataSource = data
collectionView.delegate = self
collectionView.backgroundColor = UIColor.orange
collectionView.collectionViewLayout = createLayout()
collectionView.isPagingEnabled = true
collectionView.bounces = false
collectionView.allowsSelection = true
}
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
print("WillDisplay")
guard let cell: FeaturedCell = collectionView.dequeueReusableCell(withReuseIdentifier: "FeaturedCell", for: indexPath) as? FeaturedCell else {
fatalError("Unable to dequeue FeaturedCell.")
}
cell.setCollectionViewDataSourceDelegate(featuredData, forRow: indexPath.item)
}
}
Both of these methods are being called, but the dataSource and delegates are never being set. I also followed this tutorial exactly (with a UITableView, even) and it still would not set the dataSource or delegate. What am I doing wrong?

Answer 1

I think this will help
class FeaturedCell: UICollectionViewCell {
#IBOutlet var collectionView: UICollectionView!
override init(frame: CGRect) {
super.init(frame: frame)
}
required init?(coder: NSCoder) {
super.init(coder: coder)
}
}
extension FeaturedCell {
func setCollectionViewDataSourceDelegate <T: UICollectionViewDelegate , D: FeaturedData> (delegate: T dataSource: D, forRow row: Int) {
collectionView.delegate = delegate
collectionView.dataSource = dataSource
collectionView.reloadData()
print("Reload Data")
}
}
and in the MainView
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
print("WillDisplay")
guard let cell: FeaturedCell = collectionView.dequeueReusableCell(withReuseIdentifier: "FeaturedCell", for: indexPath) as? FeaturedCell else {
fatalError("Unable to dequeue FeaturedCell.")
}
cell.setCollectionViewDataSourceDelegate(self, featuredData, forRow: indexPath.item)
}
And for the tutorial you followed this a Github link for the tutorial, compare your code with that and see where did you missed out.
Hope this will helps.

Answer 2

Solved it. The problem was that this:
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
print("WillDisplay")
guard let cell: FeaturedCell = collectionView.dequeueReusableCell(withReuseIdentifier: "FeaturedCell", for: indexPath) as? FeaturedCell else {
fatalError("Unable to dequeue FeaturedCell.")
}
cell.setCollectionViewDataSourceDelegate(featuredData, forRow: indexPath.item)
}
Needed to be changed to this:
func collectionView(_ collectionView: UICollectionView, willDisplay cell: UICollectionViewCell, forItemAt indexPath: IndexPath) {
print("WillDisplay")
guard let featuredCell = cell as? FeaturedCell else { return }
featuredCell.setCollectionViewDataSourceDelegate(featuredData, forRow: indexPath.item)
}