-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewFlowLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{

NSInteger numberOfItems = [collectionViewnumberOfItemsInSection:0];

CGFloat combinedItemWidth = (numberOfItems * collectionViewLayout.

CGFloat padding = (collectionView.frame.size.width - combinedItemWidth)/2;

    padding = padding>0 ? padding :0 ;

returnUIEdgeInsetsMake(0, padding,0, padding);

}