集合视图单元格宽度不正确

Question

after update to ios 12 and xcode 10 the collectionView with cell sizeing cell does not work correctly anymore.

i have this layout in xcode

the view is like this.

and this is how it looks now.

i have tried to set the collectionview view a widht constraint and modified in the

 func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
cell.widthConstraint.constant = UIScreen.main.bounds.width / 3

but nothing happens.

Answer 1

You were using the wrong method to set the cells size. Instead of collectionView(_:cellForItemAt:) use collectionView:layout:sizeForItemAtIndexPath:

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let itemHeight = 60
    let itemWidth = UIScreen.main.bounds.width / 3
    return CGSize(width: itemWidth, height: itemHeight)
}

Also, you can set up items size using Interface Builder s Size Inspector , but in that case, the size of your cells will be absolute. If you want it to be 1/3 of screen width, you need to use the layout delegate.