UICollectionView is scrolling when selecting a cell

Question

I'm having trouble when i try to select an item inside a UICollectionView since when I click on it it scrolls a little bit.

I know didSelectItemAtIndexPath is being called but I want to prevent the scrolling when selecting. I only want the collection view to scroll when the user is scrolling through but if the user is just tapping the cell it shouldn't move. Only should be selected.

I hope you can help me since I don't know how to prevent this problem.

Any help will be really appreciated.

This is also happening when using list layout in collectionView using functionally equivalent code to what would be done in a UITableView. — MH175, Nov 18 '21 at 01:14

score 104 · Answer 1 · answered Sep 19 '17 at 02:59

104

If you are selecting the cell programmatically with collectionview.selectItem(at: indexpath, animated: true, scrollPosition: .top) -- and since you didn't share any of your code with us, let's assume that's correct...

... then like me you might not have realized that you can use an empty set like this: collectionview.selectItem(at: indexpath, animated: true, scrollPosition: [])

answered Sep 19 '17 at 02:59

xaphod

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That is diabolical, since when were `[.foo]` and `.foo` equivalent ways to specify an `OptionSet`?! – Robert Atkins Apr 14 '21 at 09:38

CodeSmith · Answer 2 · 2016-07-26T18:14:24.227

11

This can happen if you have paging enabled and the CollectionView is manually scrolled to a position that doesn't align with the expected page boundaries. When you select the cell, it adjusts to put the CollectionView at the correct page boundaries.

edited Jul 26 '16 at 18:14

answered Dec 10 '15 at 23:10

CodeSmith

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Hi @CodeSmith, this helped me 2 years later but I do want to keep the paging behavior on my scrollView. Did you manage to get the best of both? – Edouard Barbier Nov 09 '17 at 08:28
I think my fix was to implement a custom UICollectionViewLayout and get the page size to fit correctly on the screen. The pages were a few pixels off and the layout fixed the sizing issues. – CodeSmith Nov 14 '17 at 18:30

Radu Ursache · Answer 3 · 2023-07-13T12:19:54.917

5

In Swift 5 you can do

let indexPath = IndexPath(item: 10, section: 0)

self.collectionView.selectItem(at: indexPath, animated: false, scrollPosition: .none)

in viewDidAppear or viewDidLayoutSubviews

edited Jul 13 '23 at 12:19

answered Apr 15 '20 at 14:48

Radu Ursache

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score 3 · Answer 4 · edited May 20 '17 at 00:40

3

You can try this:

collectionView.selectItem(at: newIdexPath, animated: true, scrollPosition: UICollectionViewScrollPosition(rawValue: 0))

edited May 20 '17 at 00:40

answered May 19 '17 at 13:22

zhangbangjun

41
2

score 1 · Answer 5 · answered May 13 '23 at 12:02

In my case, I solved the issue by defining a custom UICollectionViewFlowLayout.

    private var flowLayout: UICollectionViewFlowLayout {
        let flowLayout = UICollectionViewFlowLayout()
        flowLayout.sectionInset = UIEdgeInsets(top: 0, left: 5, bottom: 0, right: 5)
        flowLayout.scrollDirection = UICollectionView.ScrollDirection.horizontal
        flowLayout.minimumInteritemSpacing = 15
        return flowLayout
    }

and assigning it to the collectionView

collectionView.collectionViewLayout = flowLayout

score -3 · Answer 6 · answered Aug 16 '19 at 05:04

-3

swift 5

func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {

        collectionView.scrollToItem(at: indexPath, at: .centeredHorizontally, animated: true)

}

answered Aug 16 '19 at 05:04

Faris

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UICollectionView is scrolling when selecting a cell

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