Horizontal scrolling about ktcenterflowlayout

[Mazyod]

I just realized it's trivial to support this for horizontal scrolling using content inset .. Would be great if it just worked with your code out of the box though :)

[matthewmoss]

@Mazyod How did you adapt this to work for horizontal scrolling?

[Mazyod]

@matthewmoss I didn't. I simply replaced KTCenterFlowLayout with UICollectionViewFlowLayout for horizontal scrolling, then you simply set the layout insets to:

let cellsTotalWidth = cellsCount * (cellWidth + margin) - margin
let leftInset = min(0, (collectionView.bounds.width - cellsTotalWidth) / 2)

[keighl]

Hey @Mazyod @matthewmoss, one of you guys should make a layout that does it! If your use case is a simple/singular row. The layout would only need to adjust each UICollectionViewLayoutAttributes to have the same center as the collection view. Something like this:

- (UICollectionViewLayoutAttributes *)layoutAttributesForItemAtIndexPath:(NSIndexPath *)indexPath
{
  UICollectionViewLayoutAttributes *attrs = [super layoutAttributesForItemAtIndexPath:indexPath];
  CGFloat centerY = self.collectionView.center.y; // adjust for content insets/...
  CGPoint center = attrs.center;
  center.y = centerY;
  attrs.center = center;
  return attrs;
}

To vertically items within multiple rows, it'd be more similar to this layout. Feel free to take a stab. I don't think I'll have time to flesh that out.

[alejandroivan]

As an added note, I managed to do an horizontal layout using a UICollectionFlowLayout and messing with the insets:

- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section
{
    static const CGFloat cellSpacing = 2.0f;
    static const CGFloat cellWidth = 98.0f;

    if ( collectionView == self.collectionView ) { //
        NSInteger viewWidth = collectionView.bounds.size.width;
        NSInteger numberOfCells = [self collectionView:collectionView numberOfItemsInSection:0] ?: 1; // The number of cells. Ideally you would get this from a NSArray instead of this method (at least one element): NSInteger numberOfCells = self.yourData.count ?: 1;
        NSInteger totalCellWidth = cellWidth * ( numberOfCells );
        NSInteger totalSpacingWidth = cellSpacing * ( numberOfCells - 1 );

        CGFloat leftInset;
        if ( totalSpacingWidth + totalCellWidth > viewWidth ) {
            leftInset = cellSpacing;
        }
        else {
            leftInset = ( viewWidth % ( totalCellWidth + totalSpacingWidth ) ) / 2;
        }

        leftInset = MAX( 0, leftInset );
        NSInteger rightInset = leftInset;

        return UIEdgeInsetsMake(0, leftInset, 0, rightInset);
    }

    return UIEdgeInsetsZero; // Default insets for unhandled UICollectionViews
}

Implementing the UICollectionViewDelegateFlowLayout is, of course, mandatory:

@interface YourViewController : UIViewController <UICollectionViewDelegateFlowLayout>