Fixed header and footer support.

[dblock]

Removed leadingView and trailingView, all these do is adjust margins, we don't use that at Artsy and I don't see how this can be useful. You just say "this is a view from which to take some margin on top or bottom". Bottom does nothing really other than give you some more scroll space. I think it would be useful to be able to insert a random view on top/bottom of the scroll though without having to supply a height and a reusable view, which is https://github.com/AshFurrow/ARCollectionViewMasonryLayout/issues/8.

Added optional header in the same vein as the footer via headerHeight and headerViewClass.

Updated documentation.

[ashfurrow]

Looks good!

[orta]

breaking backward dep with leadingView and trailingView should probably mean a v.2 release FWIW

[dblock]

@orta those leading trailing views do nothing other than a leading margin. Trailing does nothing.

[ashfurrow]

So where did we fall on this? Good to merge?

[orta]

me and db paired on it earlier, he might just push new stuff

[ashfurrow]

Cool cool.

[dblock]

Sat down with @orta and rewritten this whole mess using ARCollectionViewMasonryLayoutDelegate. So now if you want to add a header or a footer, you no longer need to manipulate the layout, you do this on the view-controller.

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    // return a header and/or footer view, must be a UICollectionReusableView
    // kind is one of UICollectionElementKindSectionHeader or UICollectionElementKindSectionFooter
    UICollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:kind forIndexPath:indexPath];
    view.backgroundColor = [UIColor whiteColor];
    return view;
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(ARCollectionViewMasonryLayout *)collectionViewLayout dimensionForHeaderAtIndexPath:(NSIndexPath *)indexPath
{
    return 20; // header length
}

- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(ARCollectionViewMasonryLayout *)collectionViewLayout dimensionForFooterAtIndexPath:(NSIndexPath *)indexPath
{
    return 10; // footer length
}

This is ready to merge if green, but needs another code-review.

[ashfurrow]

Cool. Will do.

[ashfurrow]

Looks solid.

[dblock]

This is :green_apple: