Answer for Objective-C
and Swift2.0
: How to center align the cells of a UICollectionView?
I usually would try to convert the Swift2.0
answer to the Swift3.0
solution, however the method:
func collectionView(collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAtIndex section: Int) -> UIEdgeInsets {
let edgeInsets = (screenWight - (CGFloat(elements.count) * 50) - (CGFloat(elements.count) * 10)) / 2
return UIEdgeInsetsMake(0, edgeInsets, 0, 0);
}
doesn't seem to exist in Swift3.0
,and the only other method I found that seems useful is:
func collectionView(_ collectionView: UICollectionView, transitionLayoutForOldLayout fromLayout: UICollectionViewLayout, newLayout toLayout: UICollectionViewLayout) -> UICollectionViewTransitionLayout {
<#code#>
}
but I am unsure how to implement it correctly.
How to center align the cells of a UICollectionView
in Swift3.0
?
(A simple and general solution for iOS and tvOS would be perfect)
This ended up being the solution I used. Read the code comments for a better understanding. Swift 5
func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, insetForSectionAt section: Int) -> UIEdgeInsets {
//Where elements_count is the count of all your items in that
//Collection view...
let cellCount = CGFloat(elements_count)
//If the cell count is zero, there is no point in calculating anything.
if cellCount > 0 {
let flowLayout = collectionViewLayout as! UICollectionViewFlowLayout
let cellWidth = flowLayout.itemSize.width + flowLayout.minimumInteritemSpacing
//20.00 was just extra spacing I wanted to add to my cell.
let totalCellWidth = cellWidth*cellCount + 20.00 * (cellCount-1)
let contentWidth = collectionView.frame.size.width - collectionView.contentInset.left - collectionView.contentInset.right
if (totalCellWidth < contentWidth) {
//If the number of cells that exists take up less room than the
//collection view width... then there is an actual point to centering them.
//Calculate the right amount of padding to center the cells.
let padding = (contentWidth - totalCellWidth) / 2.0
return UIEdgeInsets(top: 0, left: padding, bottom: 0, right: padding)
} else {
//Pretty much if the number of cells that exist take up
//more room than the actual collectionView width, there is no
// point in trying to center them. So we leave the default behavior.
return UIEdgeInsets(top: 0, left: 40, bottom: 0, right: 40)
}
}
return UIEdgeInsets.zero
}