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

Question

I added UICollectionView by code.
Now, the app crash with message: UICollectionView must be initialized with a non-nil layout parameter.
Do

Answer 1

Swift 3.0, Swift 4.0 and Swift 5.0

It's work for me.

let collectionView = UICollectionView(frame: CGRect.zero, collectionViewLayout: UICollectionViewFlowLayout.init())

In Method (inside viewDidLoad)

if let flowLayout = collectionView.collectionViewLayout as? UICollectionViewFlowLayout {
    flowLayout.scrollDirection = .horizontal
}