Ios – Aligning collection view cells to fit exactly 3 per row

iosswiftuicollectionviewxcode

I am trying to make a collection view of images, so that there are 3 per row, with no spacing in between.

My collection view data sources are:

func numberOfSections(in collectionView: UICollectionView) -> Int {
    return 1
}

func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
    return posts.count
}

and this is how it's set up in my storyboard (imageView width is 125, a third of the 375 screen width):

enter image description here

However when I run the app and add some photos, it looks like this:

enter image description here

How can I fix this so that I see 3 images per row? Thanks for any help!

Best Answer

You have to implement the

UICollectionViewDelegateFlowLayout

for the spacing stuff.

Set the size of the collectionViewCells like this:

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
    let yourWidth = collectionView.bounds.width/3.0
    let yourHeight = yourWidth

    return CGSize(width: yourWidth, height: yourHeight)
}

You can also add these functions to get your spacing of the collectionViewCells correct:

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

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumInteritemSpacingForSectionAt section: Int) -> CGFloat {
    return 0
}

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, minimumLineSpacingForSectionAt section: Int) -> CGFloat {
    return 0
}
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