Provide the way to configure layout after applied.

[royhsu]

func applyLayout(
    _ layout: CollectionViewLayout.Type, 
    configure: ( (CollectionViewLayout) -> Void )? = nil
) { ... }

[royhsu]

Alternative

collectionView.applyLayout(MyLayout.self)

let myLayout = collectionView.layout as? MyLayout

// configure myLayout here