UICollectionView doesn't bounce when datasource has only 1 item

Question

I have a UICollectionView with a custom UICollectionViewFlowLayout. It scrolls horizontally and only shows one item at a time (full height). I have pagingEnabled = YES so that it sticks to pages.

The UICollectionView shows photos within a particular day. I initially had buttons to change the day +/- 1 day, but I thought it would be neat if the user could pull on the collection view past the first or last image (past a predetermined threshold) to change the day. I implemented this using the UIScrollView delegate methods and it works great...... if there are 2 or more items in the collection view.

This is hard to describe, but if there is only 1 item, it doesn't allow me to pull the item past it's bounds. I.E. there is no bounce to it.

I'd like to have this behavior, but I need to overcome this problem first. I'm thinking that if I removed pagingEnabled = YES and used targetContentOffsetForProposedContentOffset:proposedContentOffset:withScrollingVelocity, that I may be able to get it to work but I really enjoy the snappy behavior that paging enables. (They are mutually exclusive).

Any ideas on this?

score 136 · Accepted Answer · edited May 28 '14 at 09:32

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UICollectionView has the properties alwaysBounceHorizontal and alwaysBounceVertical. Setting the horizontal to YES did the trick.

edited May 28 '14 at 09:32

Rafał Sroka

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answered Aug 22 '13 at 21:19

VaporwareWolf

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To enable this inside the Interface Builder — use the option called "Bounce Vertically". – Anthony Dmitriyev Feb 25 '14 at 15:20
`alwaysBounceHorizontal` and `alwaysBounceVertical` are originated from view `UIScrollView`. – tounaobun Jul 08 '15 at 05:09
So can I say that `UITableView` has this property set to `YES` as default since it can be bounds? – xi.lin Aug 20 '15 at 03:36
For me assigning *layout* instance in `viewDidLayoutSubviews` was the issue. – Paresh Thakor Sep 04 '21 at 18:11

score 4 · Answer 2 · answered Dec 13 '16 at 09:59

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Thanks for @VaporwareWolf ,the answer is correct. I want to add a supplement that:

DO NOT forget setting the bounces property to YES at the same time（through storyboard or your code）.

answered Dec 13 '16 at 09:59

guozqzzu

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UICollectionView doesn't bounce when datasource has only 1 item

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