You can use the collectionView:layout:insetForSectionAtIndex: method for your UICollectionView or set the sectionInset property of the UICollectionViewFlowLayout object attached to your UICollectionView:

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{    return UIEdgeInsetsMake(top, left, bottom, right);}

or

UICollectionViewFlowLayout *aFlowLayout = [[UICollectionViewFlowLayout alloc] init];[aFlowLayout setSectionInset:UIEdgeInsetsMake(top, left, bottom, right)];

Updated for Swift 5

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {       return UIEdgeInsets(top: 25, left: 15, bottom: 0, right: 5)    }

Setting up insets in Interface Builder like shown in the screenshot below

Will result in something like this:

To add spacing on the entire UICollectionView:

UICollectionViewFlowLayout *flow = (UICollectionViewFlowLayout*) collection.collectionViewLayout;flow.sectionInset = UIEdgeInsetsMake(topMargin, left, bottom, right);

To play with the spacing between elements of the same row (column if you're scrolling horizontally), and their sizes:

flow.itemSize = ...;flow.minimumInteritemSpacing = ...;