Error: UICollectionView must be initialized with a non-nil layout parameter

Question

I am trying to create a Facebook messenger like application from a youtube tutorial. I have a home page where the user click BarButton to open the chats. The Home page works

Answer 1

Probably when you present your ChatViewController you have something like:

let chatVC = ChatViewController()

But according to Apple doc:

class UICollectionViewController

When you initialize the controller, using the init(collectionViewLayout:) method, you specify the layout the collection view should have.

So you need:

 let chatVC = ChatViewController(collectionViewLayout: UICollectionViewFlowLayout())