gistfile1.txt

func collectionView(collectionView: UICollectionView, cellForItemAtIndexPath indexPath: NSIndexPath) -> UICollectionViewCell {
        guard let charge = charges[indexPath.item] as Charge else { fatalError("Invalid index") }
        guard let cell   = collectionView.dequeueReusableCellWithReuseIdentifier(CellIdentifier, forIndexPath: indexPath) as? ChargeKeypadCell else { fatalError("Invalid Cell for charge view") }
        cell.charge      = charge 
        
        return cell
}