UICollectionViewFlowLayout *layout = [UICollectionViewFlowLayout new];
layout.scrollDirection = UICollectionViewScrollDirectionVertical;
layout.minimumInteritemSpacing = 2.0f;
layout.minimumLineSpacing = 2.0f;
	
PMBrowsingCollectionView *collectionView = [PMBrowsingCollectionView collectionViewWithFrame:self.view.bounds
                                                                            collectionViewLayout:layout];
collectionView.delegate = self;
collectionView.dataSource = self;
[collectionView registerClass:[UICollectionViewCell class]
            forCellWithReuseIdentifier:@"cellReuseIdentifier"];
[collectionView registerClass:[UICollectionReusableView class]
            forSupplementaryViewOfKind:UICollectionElementKindSectionHeader
                   withReuseIdentifier:@"headerReuseIdentifier"];
[self.view addSubview:collectionView];

- (UICollectionViewCell *)collectionView:(PMBrowsingCollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
	UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellReuseIdentifier" forIndexPath:indexPath];
	NSUInteger normalizedIndex = [collectionView normalizeItemIndex:indexPath.item forSection:indexPath.section];
	/*
	* Configure cell based on indexPath.section and normalizedIndex
	*/
	return cell;
}

- (CGFloat) collectionView:(PMBrowsingCollectionView *)collectionView shadowRadiusForSection:(NSInteger)section
{
    return 20.0f;
}

- (UIColor *) collectionView:(PMBrowsingCollectionView *)collectionView shadowColorForSection:(NSInteger)section
{
    return [UIColor blackColor];
}

// Only called when section is in a collapsed state.
- (void) collectionView:(PMBrowsingCollectionView *)collectionView willCenterItemAtIndexPath:(NSIndexPath *)indexPath
{
	NSUInteger normalizedIndex = [collectionView normalizeIndex:indexPath.item];
	DLog(@"Will center cell at section index %d, item index %d", indexPath.section, normalizedIndex);
}