How to center horizontally UICollectionView Cells?

Question

I have done some research, but I couldn't find any code example on how to center cells in a UICollectionView horizontally.

instead of the first cell being like this X00, I want it to be like this 0X0. is there any way to accomplish this?

EDIT:

to visualize what I want:

I need it to look like version B when there is only one element in the CollectionView. When I got more than one element, then it should be like version A but with more elements.

At the moment it looks like Version A when I have only 1 element, and I wonder how I can make it look like B.

Thanks for the help!

Answer 1

Its not a good idea to use a library, if your purpose is only this i.e to centre align.

Better you can do this simple calculation in your collectionViewLayout function.

func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets {

    let totalCellWidth = CellWidth * CellCount
    let totalSpacingWidth = CellSpacing * (CellCount - 1)

    let leftInset = (collectionViewWidth - CGFloat(totalCellWidth + totalSpacingWidth)) / 2
    let rightInset = leftInset

    return UIEdgeInsets(top: 0, left: leftInset, bottom: 0, right: rightInset)
}

Answer 2

Swift 5.1

func centerItemsInCollectionView(cellWidth: Double, numberOfItems: Double, spaceBetweenCell: Double, collectionView: UICollectionView) -> UIEdgeInsets {
    let totalWidth = cellWidth * numberOfItems
    let totalSpacingWidth = spaceBetweenCell * (numberOfItems - 1)
    let leftInset = (collectionView.frame.width - CGFloat(totalWidth + totalSpacingWidth)) / 2
    let rightInset = leftInset
    return UIEdgeInsets(top: 0, left: leftInset, bottom: 0, right: rightInset)
}

Swift 4.2

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {

    let totalCellWidth = 80 * collectionView.numberOfItems(inSection: 0)
    let totalSpacingWidth = 10 * (collectionView.numberOfItems(inSection: 0) - 1)

    let leftInset = (collectionView.layer.frame.size.width - CGFloat(totalCellWidth + totalSpacingWidth)) / 2
    let rightInset = leftInset

    return UIEdgeInsets(top: 0, left: leftInset, bottom: 0, right: rightInset)

}

Swift 3

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets {

        let totalCellWidth = 80 * collectionView.numberOfItems(inSection: 0)
        let totalSpacingWidth = 10 * (collectionView.numberOfItems(inSection: 0) - 1)

        let leftInset = (collectionView.layer.frame.size.width - CGFloat(totalCellWidth + totalSpacingWidth)) / 2
        let rightInset = leftInset

        return UIEdgeInsetsMake(0, leftInset, 0, rightInset)

    }

don't forget to add the protocol

UICollectionViewDelegateFlowLayout

Answer 3

Try this for Swift 4

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
        let cellWidth : CGFloat = 165.0
        
        let numberOfCells = floor(collectionView.frame.size.width / cellWidth)
        let edgeInsets = (collectionView.frame.size.width - (numberOfCells * cellWidth)) / (numberOfCells + 1)
        
        return UIEdgeInsetsMake(15, edgeInsets, 0, edgeInsets)
    }

Add your cellWidth instead 165.0