Initialize a UICollectionView with a CGRect frame:

Swift:

let collection = UICollectionView(frame: CGRect(x: 0, y: 0, width: 200, height: 21))

Objective C:

UICollectionView *collection = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 0, 200, 21)];

You can also create a UICollectionView in Interface Builder