On an iPhone 5s the left and right cards are not visible

[grundid]

The space between the cards is too large for an iPhone 5s, so the user sees only one card. It's not obvious how to interact with the collection in this situation.

[0ber]

In your ViewController need to set item size

override func viewDidLoad() {
    itemSize = CGSize(width: 214, height: 264)
    super.viewDidLoad()

    // register cell
    let nib = UINib(nibName: "NibName", bundle: nil)
    collectionView?.registerNib(nib, forCellWithReuseIdentifier: "CellIdentifier")
}

and if you use this delegates method:

override func collectionView(collectionView: UICollectionView, willDisplayCell cell: UICollectionViewCell, forItemAtIndexPath indexPath: NSIndexPath)

must call super method:

super.collectionView(collectionView, willDisplayCell: cell, forItemAtIndexPath: indexPath)