ios - cellForItemAt never called in a class extends UICollectionViewController

Question

I followed this video to create the UICollectionViewController, but the collection cells do not appear as expected. I added some print messages, and it turns out that numberOfItemsInSection is called, but cellForItemAt function is never called. Also, in viewDidLoad method, I printed out collectionView?.contentSize and it's (0.0, 0.0). Not sure what's the problem. Can anyone help explain?

More: I found the problem might be that I didn't use pushViewController to navigate but use performSegue, so I didn't set UICollectionDelegateFlowLayout as the video did... Any way to fix it?

Answer 1

Did you make sure that the function numberOfItemsInSection is return at least 1 or more? It will be helpful if you can paste some of your code.