UICollectionViewDelegateFlowLayout(GesturePassword).swift

extension ViewController: UICollectionViewDelegateFlowLayout {
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let width = collectionView.bounds.width / CGFloat(row * 2 - 1)
        return CGSize(width: width, height: width)
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
        let width = collectionView.bounds.width / CGFloat(row * 2 - 1)
        return width
    }
    
    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
        let width = collectionView.bounds.width / CGFloat(row * 2 - 1)
        return width
    }
}