How do you determine spacing between cells in UICollectionView flowLayout

Question

I have a UICollectionView with a flow layout and each cell is a square. How do I determine the spacing between each cells on each row? I can\'t seem to find the appropriate

Answer 1

A cleaner swift version for people interested, based on Chris Wagner's answer:

class AlignLeftFlowLayout: UICollectionViewFlowLayout {

    var maximumCellSpacing = CGFloat(9.0)

    override func layoutAttributesForElementsInRect(rect: CGRect) -> [AnyObject]? {
        let attributesToReturn = super.layoutAttributesForElementsInRect(rect) as? [UICollectionViewLayoutAttributes]

        for attributes in attributesToReturn ?? [] {
            if attributes.representedElementKind == nil {
                attributes.frame = self.layoutAttributesForItemAtIndexPath(attributes.indexPath).frame
            }
        }

        return attributesToReturn
    }

    override func layoutAttributesForItemAtIndexPath(indexPath: NSIndexPath) -> UICollectionViewLayoutAttributes! {
        let curAttributes = super.layoutAttributesForItemAtIndexPath(indexPath)
        let sectionInset = (self.collectionView?.collectionViewLayout as UICollectionViewFlowLayout).sectionInset

        if indexPath.item == 0 {
            let f = curAttributes.frame
            curAttributes.frame = CGRectMake(sectionInset.left, f.origin.y, f.size.width, f.size.height)
            return curAttributes
        }

        let prevIndexPath = NSIndexPath(forItem: indexPath.item-1, inSection: indexPath.section)
        let prevFrame = self.layoutAttributesForItemAtIndexPath(prevIndexPath).frame
        let prevFrameRightPoint = prevFrame.origin.x + prevFrame.size.width + maximumCellSpacing

        let curFrame = curAttributes.frame
        let stretchedCurFrame = CGRectMake(0, curFrame.origin.y, self.collectionView!.frame.size.width, curFrame.size.height)

        if CGRectIntersectsRect(prevFrame, stretchedCurFrame) {
            curAttributes.frame = CGRectMake(prevFrameRightPoint, curFrame.origin.y, curFrame.size.width, curFrame.size.height)
        } else {
            curAttributes.frame = CGRectMake(sectionInset.left, curFrame.origin.y, curFrame.size.width, curFrame.size.height)
        }

        return curAttributes
    }
}