Horizontal and vertical collectionVIews in the same view Controller

I need to show in a viewController two collectionViews.

At the top a single row and on then on the rest of the view a collectionView with vertical scrolling and two columns.

That's the current piece of code to show both collectionViews:

@IBOutlet weak var collectionViewMarcas: UICollectionView!

var marcas = [Marcas]()

@IBOutlet weak var collectionViewDispositivos: UICollectionView!

var dispositivos = [Dispositivos]()


func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {

    if collectionView == collectionViewMarcas {
        return marcas.count
    }

        return dispositivos.count



}




   func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

      // print("MARCA:"+marcas[indexPath.row].nombre)
   }


   func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {


    if collectionView == self.collectionViewMarcas {
              let cellMarcas = collectionView.dequeueReusableCell(withReuseIdentifier: "marca", for: indexPath) as! MarcasCollectionViewCell
               let foto_marca = marcas[indexPath.row].icono
                       print(foto_marca)


                       let url = URL(string: "https://.../iconos/"+foto_marca)

                       UIImage.loadFrom(url: url!) { image in
                           cellMarcas.icono_marca.image = image

                       }


              return cellMarcas
          }

          else {
               let cellDisp = collectionView.dequeueReusableCell(withReuseIdentifier: "dispositivo", for: indexPath) as! DispositivosCollectionViewCell

             let foto_dispos = dispositivos[indexPath.row].foto_dispositivo
             print(foto_dispos)

        let modelo = dispositivos[indexPath.row].modelo_del_dispositivo
        cellDisp.modelo_disp.text = modelo
        let precio = dispositivos[indexPath.row].precio_dispositivo + " €"
        cellDisp.precio_disp.text = precio
        let marca = dispositivos[indexPath.row].logo_marca
        let urlmarca = URL(string: "https://../iconos/"+marca)
        UIImage.loadFrom(url: urlmarca!) { image in
                       cellDisp.marca_logo.image = image

                   }
        let urlfoto = URL(string: "https://.../dispositivos/"+foto_dispos)

        UIImage.loadFrom(url: urlfoto!) { image in
            cellDisp.foto_disp.image = image

        }

              return cellDisp
          }


   }

Here you have a screenshot:

I have tried implementing UICollectionViewDelegateFlowLayout and then

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let padding: CGFloat =  50
        let collectionViewSize = collectionView.frame.size.width - padding

        return CGSize(width: collectionViewSize/2, height: collectionViewSize/2)
    }

This implementation works fine for the vertical collectionView, but it also changes the horizontal one.

How could I get only the vertical layout changed?

You need To Return both Collection view Size collectionViewLayout delegate method

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {

//You only apply the changes to collectionViewMarcas
 if collectionView == self.collectionViewMarcas 
 {
    let padding: CGFloat =  50
    let collectionViewSize = collectionView.frame.size.width - padding

    return CGSize(width: collectionViewSize/2, height: collectionViewSize/2)
  }

  // Here Below Line You need To return collectionViewDispositivos cell size
  return CGSize(width: 60, height: 60)
}