• Official UIKit
• xCode 11 with no storyboard

• UINavigationController

UICollectionViewCell - element inside a controller (can be a friend entry in whatsapp/messenger)

class FriendCell: UICollectionViewCell {
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupViews()
    }
 
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
 
    func setupViews() {
        backgroundColor = UIColor.blue
    }
}

To register UICollectionViewCell to Controller add in viewDidLoad()

collectionView.register(FriendCell.self, forCellWithReuseIdentifier: cellId)

Making UICollectionViewCell to take full row

func collectionView(_ collectionView: UICollectionView, layout collectionviewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    return CGSize(width: view.frame.width, height: 100)
}