CollectionView Cells Not showing - ios

Question

I'm trying to show images in a UICollectionView. The code below is responsible for showing the cell.
super.viewWillAppear(animated)
memes = appDelegate.memes
collectionView?.reloadData()
// Uncomment the following line to preserve selection between presentations
// self.clearsSelectionOnViewWillAppear = false
let space:CGFloat = 3.0
let dimension = (view.frame.size.width - (2 * space)) / 3.0
flowLayout.minimumInteritemSpacing = space
flowLayout.minimumLineSpacing = space
flowLayout.itemSize = CGSize(width: dimension, height: dimension)
flowLayout.sectionInset = UIEdgeInsets(top: 1.0, left: 1.0, bottom: 1.0, right: 1.0)
}
and
override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "MemeCollectionViewCell", for: indexPath) as! MemeCollectionViewCell
let meme = memes[(indexPath as NSIndexPath).row]
cell.memeImageView?.image = meme.meme
// Configure the cell
return cell
}
All I see is a blank view controller. When I click the screen, the details VC popups up (as it should). It seems like the information for the view is there but just isn't being rendered on the screen. What changes do I need to make in order to ensure the images show?

Answer 1

Your collectionview delegates are not being called.
you have to write
collectionview.delegate = self
collectionview.dataSource = self
And if the delegates are being called, please check if meme.meme has and image.

Answer 2

it turns out I didn't have the module name set in the collection view controller in storyboard.

Answer 3

1) use default method to provide flowLayout to a collectionView
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
return CGSize(width: width/3, height: 100)
}
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets{
return UIEdgeInsetsMake(0, 0, 0, 0)
}
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat{
return 0
}
public func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat{
return 0
}
2) make sure you had initialised in code before you reload your collectionViw
collectionview.delegate = self
collectionview.dataSource = self
3) add breakpoints in numberOfItemsInSectionafter relaoding and check do your meme array really have value the you reload CollectionView and if yes , of course it will after this go to CellforRowAt and check do your memeImageView is getting value or not . print image view using breakpoint just for try

Answer 4

I faced the same issue, when I debugged the issue it was that collectionView is not getting height to be displayed and delegate method cellForItem was not even working.
Solution:
I set me leading and trailing constraint to the parentView outside stackView.
My view hierarchy was parentView->stackView->collectionView.
Comment if you have any question.